Add support for Python 3.8.7

Closes @W-7791264@.
Release v186 (#1124 )
2026-06-05 23:10:16 +00:00 · 2020-11-20 11:49:34 +00:00 · 2020-11-18 13:26:39 +00:00 · 2020-11-17 15:19:48 +00:00 · 2020-11-13 13:10:52 +00:00 · 2020-11-12 18:40:31 +00:00
108 changed files with 877 additions and 3053 deletions
@@ -0,0 +1,6 @@
 {
  "productTag": "a1aB0000000MR0RIAW",
  "issueTypeLabels": { "gus: story": "USER STORY", "gus: bug": "BUG P3" },
  "defaultBuild": "Heroku Unscheduled",
  "statusWhenClosed": "CLOSED"
 }
@@ -0,0 +1,15 @@
 version: 2
 updates:
  - package-ecosystem: "pip"
    directory: "/"
    schedule:
      interval: "weekly"
    labels:
      - "c: dependencies"
  - package-ecosystem: "bundler"
    directory: "/"
    schedule:
      interval: "weekly"
    labels:
      - "c: dependencies"
@@ -1,7 +0,0 @@
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v2.3.0
    hooks:
    -   id: check-yaml
    -   id: end-of-file-fixer
    -   id: trailing-whitespace
@@ -1,5 +1,5 @@
 language: minimal
-dist: bionic
+dist: focal
 branches:
  only:
  - main
@@ -12,22 +12,17 @@ jobs:
  - name: Bash linting (shellcheck)
    script: make check
  - name: Hatchet integration tests
-    if: env(TRAVIS_PULL_REQUEST_SLUG) = env(TRAVIS_REPO_SLUG)
+    if: env(HEROKU_API_USER) IS present AND env(HEROKU_API_KEY) IS present
    language: ruby
    rvm:
-      - 2.6.6
+      - 2.7
    before_script:
      - gem install bundler -v 1.16.2
    script:
      - bundle exec hatchet ci:setup
    script:
      - PARALLEL_SPLIT_TEST_PROCESSES=11 bundle exec parallel_split_test spec/hatchet/
 env:
  jobs:
    - STACK=cedar-14 TEST_CMD=test/run-deps
    - STACK=cedar-14 TEST_CMD=test/run-versions
    - STACK=cedar-14 TEST_CMD=test/run-features
    - STACK=heroku-16 TEST_CMD=test/run-deps
    - STACK=heroku-16 TEST_CMD=test/run-versions
    - STACK=heroku-16 TEST_CMD=test/run-features
@@ -35,10 +30,12 @@ env:
    - STACK=heroku-18 TEST_CMD=test/run-deps
    - STACK=heroku-18 TEST_CMD=test/run-versions
    - STACK=heroku-18 TEST_CMD=test/run-features
    - STACK=heroku-20 TEST_CMD=test/run-deps
    - STACK=heroku-20 TEST_CMD=test/run-versions
    - STACK=heroku-20 TEST_CMD=test/run-features
  global:
    - HATCHET_RETRIES=3
    - IS_RUNNING_ON_CI=true
    - HATCHET_APP_LIMIT=80
    - HATCHET_DEPLOY_STRATEGY=git
    - secure: yjtlPE5FbVxTKnjUy/tZUBgSEf4qADD3QOxtgziuid73S0U/1IEXlMGFULsQzIjtlHKmHeywZqpVVEpthIH4RuT7uoX1Pb7SSM/g0T8fT3VoEFbFK1uYl0oZQbUS4Klxv9tPiumj8if3m6ULEGIz1X0wZcMOC0tMLwVCnwmap0E=
    - secure: ZeFTHWwnpIKE9nAqs88ocmiQh7bKce84lilGm5J23nf3N6V4wNyLwqlkvsM008WGBCaOg9AUx7ZunasT0ANsR5gLP3eV2UUg7ILdRgV2Gy13eNRFheC4PHdN92RqQ3aKoqlIv2K999xlhVjod0NzhkQQXB6PddfQINbuU7ks6As=
@@ -2,6 +2,69 @@
 ## Unreleased
 - Python 3.8.7 is now available (CPython) (#1122).
 ## v186 (2020-11-18)
 - Update the `BUILD_WITH_GEO_LIBRARIES` error message (#1121).
 - Switch NLTK feature detection away from `sp-grep` (#1119).
 - Switch Django collectstatic feature detection away from `sp-grep` (#1119).
 - Remove vendored `sp-grep` script (#1119).
 - Remove vendored `pip-diff` script (#1118).
 - Remove vendored `pip-grep` script (#1116).
 ## v185 (2020-11-12)
 - Error if the unsupported `BUILD_WITH_GEO_LIBRARIES` env var is set (#1115).
 - Remove deprecated GDAL/GEOS/PROJ support (#1113).
 - Remove vendored `jq` binary (#1112).
 - Remove redundant Mercurial install step (#1111).
 - Remove support for the Cedar-14 stack (#1110).
 ## v184 (2020-10-21)
 - Vendor buildpack-stdlib instead of fetching from S3 (#1100).
 - Fix metric names for metrics emitted within `sub_env` (#1099).
 ## v183 (2020-10-12)
 - Add support for Heroku-20 (#968).
 ## v182 (2020-10-06)
 - Python 3.9.0 is now available (CPython) (#1090).
 - Migrate from the `lang-python` S3 bucket to `heroku-buildpack-python` (#1089).
 - Remove `vendor/shunit2` (#1086).
 - Replace `BUILDPACK_VENDOR_URL` and `USE_STAGING_BINARIES` with `BUILDPACK_S3_BASE_URL` (#1085).
 ## v181 (2020-09-29)
 - PyPy 2.7 and 3.6, version 7.3.2 are now available (Note: PyPy support is in beta) (#1081).
 ## v180 (2020-09-24)
 - Python 3.8.6 is now available (CPython) (#1072).
 ## v179 (2020-09-23)
 - Remove duplicate pipenv metric event (#1070).
 - Emit metrics for how the Python version was chosen for an app (#1069).
 - Emit Python version metric events for all builds, not just clean installs (#1066).
 ## v178 (2020-09-07)
 - Python 3.5.10 is now available (CPython) (#1062).
 ## v177 (2020-08-18)
 - Python 3.6.12 and 3.7.9 are now available (CPython) (#1054).
 - The default Python version for new apps is now 3.6.12 (previously 3.6.11) (#1054).
 ## v176 (2020-08-12)
 - Rebuild the Python 3.4.10 archives with the correct version of Python (#1048).
 - Fix the security update version check message for apps using PyPy (#1040).
 - Remove `vendor/test-utils` (#1043).
 ## v175 (2020-08-05)
@@ -1,68 +1,50 @@
 GEM
  remote: https://rubygems.org/
  specs:
-    activesupport (6.0.3.1)
+    diff-lcs (1.4.4)
      concurrent-ruby (~> 1.0, >= 1.0.2)
      i18n (>= 0.7, < 2)
      minitest (~> 5.1)
      tzinfo (~> 1.1)
      zeitwerk (~> 2.2, >= 2.2.2)
    concurrent-ruby (1.1.6)
    diff-lcs (1.3)
    erubis (2.7.0)
-    excon (0.73.0)
+    excon (0.78.0)
-    heroics (0.0.25)
+    heroics (0.1.1)
      erubis (~> 2.0)
      excon
      moneta
      multi_json (>= 1.9.2)
-    heroku_hatchet (5.0.3)
+    heroku_hatchet (7.3.3)
      excon (~> 0)
-      minitest-retry (~> 0.1.9)
+      platform-api (~> 3)
      platform-api (~> 2)
      repl_runner (~> 0.0.3)
      rrrretry (~> 1)
-      thor (~> 0)
+      thor (~> 1)
      threaded (~> 0)
    i18n (1.8.2)
      concurrent-ruby (~> 1.0)
    minitest (5.14.1)
    minitest-retry (0.1.9)
      minitest (>= 5.0)
    moneta (1.0.0)
-    multi_json (1.14.1)
+    multi_json (1.15.0)
-    parallel (1.19.1)
+    parallel (1.19.2)
-    parallel_split_test (0.7.0)
+    parallel_split_test (0.8.0)
      parallel (>= 0.5.13)
      rspec (>= 3.1.0)
-    platform-api (2.2.0)
+    platform-api (3.0.0)
-      heroics (~> 0.0.25)
+      heroics (~> 0.1.1)
      moneta (~> 1.0.0)
-    rake (12.3.3)
+      rate_throttle_client (~> 0.1.0)
-    repl_runner (0.0.3)
+    rake (13.0.1)
-      activesupport
+    rate_throttle_client (0.1.2)
    rrrretry (1.0.0)
-    rspec (3.8.0)
+    rspec (3.10.0)
-      rspec-core (~> 3.8.0)
+      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.8.0)
+      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.8.0)
+      rspec-mocks (~> 3.10.0)
-    rspec-core (3.8.0)
+    rspec-core (3.10.0)
-      rspec-support (~> 3.8.0)
+      rspec-support (~> 3.10.0)
-    rspec-expectations (3.8.1)
+    rspec-expectations (3.10.0)
      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
+      rspec-support (~> 3.10.0)
-    rspec-mocks (3.8.0)
+    rspec-mocks (3.10.0)
      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
+      rspec-support (~> 3.10.0)
-    rspec-retry (0.6.1)
+    rspec-retry (0.6.2)
      rspec-core (> 3.3)
-    rspec-support (3.8.0)
+    rspec-support (3.10.0)
-    thor (0.20.3)
+    thor (1.0.1)
    thread_safe (0.3.6)
    threaded (0.0.4)
    tzinfo (1.2.7)
      thread_safe (~> 0.1)
    zeitwerk (2.3.0)
 PLATFORMS
  ruby
@@ -1,55 +1,61 @@
 # These targets are not files
-.PHONY: check test buildenv-heroku-16 buildenv-heroku-18 tools
+.PHONY: check test compile builder-image buildenv deploy-runtimes tools
 STACK ?= heroku-18
 STACKS ?= heroku-16 heroku-18 heroku-20
 TEST_CMD ?= test/run-versions && test/run-features && test/run-deps
 FIXTURE ?= test/fixtures/requirements-standard
 ENV_FILE ?= builds/dockerenv.default
 BUILDER_IMAGE_PREFIX := heroku-python-build
 ifeq ($(STACK),cedar-14)
 	# Cedar-14 doesn't have a build image varient.
 	IMAGE_TAG := heroku/cedar:14
 else
 # Converts a stack name of `heroku-NN` to its build Docker image tag of `heroku/heroku:NN-build`.
-	IMAGE_TAG := heroku/$(subst -,:,$(STACK))-build
+STACK_IMAGE_TAG := heroku/$(subst -,:,$(STACK))-build
 endif
 check:
 	@shellcheck -x bin/compile bin/detect bin/release bin/test-compile bin/utils bin/warnings bin/default_pythons
-	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/gdal bin/steps/geo-libs bin/steps/mercurial bin/steps/nltk bin/steps/pip-install bin/steps/pip-uninstall bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/pylibmc bin/steps/python
+	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/nltk bin/steps/pip-install bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/python
 	@shellcheck -x bin/steps/hooks/*
 test:
 	@echo "Running tests using: STACK=$(STACK) TEST_CMD='$(TEST_CMD)'"
 	@echo ""
 	@docker run --rm -it -v $(PWD):/buildpack:ro -e "STACK=$(STACK)" "$(IMAGE_TAG)" bash -c 'cp -r /buildpack /buildpack_test && cd /buildpack_test && $(TEST_CMD)'
 	@echo ""
 buildenv-heroku-16:
 	@echo "Creating build environment (heroku-16)..."
 	@echo
-	@docker build --pull -f $(shell pwd)/builds/heroku-16.Dockerfile -t python-buildenv-heroku-16 .
+	@docker run --rm -it -v $(PWD):/buildpack:ro -e "STACK=$(STACK)" "$(STACK_IMAGE_TAG)" bash -c 'cp -r /buildpack /buildpack_test && cd /buildpack_test && $(TEST_CMD)'
 	@echo
 compile:
 	@echo "Running compile using: STACK=$(STACK) FIXTURE=$(FIXTURE)"
 	@echo
 	@docker run --rm -it -v $(PWD):/src:ro -e "STACK=$(STACK)" -w /buildpack "$(STACK_IMAGE_TAG)" \
 		bash -c 'cp -r /src/{bin,vendor} /buildpack && cp -r /src/$(FIXTURE) /build && mkdir /cache /env && bin/compile /build /cache /env'
 	@echo
 builder-image:
 	@echo "Generating binary builder image for $(STACK)..."
 	@echo
 	@docker build --pull -f builds/$(STACK).Dockerfile -t "$(BUILDER_IMAGE_PREFIX)-$(STACK)" .
 	@echo
 buildenv: builder-image
 	@echo "Starting build environment for $(STACK)..."
 	@echo
 	@echo "Usage..."
 	@echo
-	@echo "  $$ export AWS_ACCESS_KEY_ID=foo AWS_SECRET_ACCESS_KEY=bar  # Optional unless deploying"
+	@echo "  $$ bob build runtimes/python-X.Y.Z"
 	@echo "  $$ bob build runtimes/python-2.7.13"
 	@echo "  $$ bob deploy runtimes/python-2.7.13"
 	@echo
-	@docker run -it --rm python-buildenv-heroku-16
+	@docker run --rm -it --env-file="$(ENV_FILE)" -v $(PWD)/builds:/app/builds "$(BUILDER_IMAGE_PREFIX)-$(STACK)" bash
-buildenv-heroku-18:
+deploy-runtimes:
-	@echo "Creating build environment (heroku-18)..."
+ifndef RUNTIMES
 	$(error No runtimes specified! Use: "make deploy-runtimes RUNTIMES='python-X.Y.Z ...' [STACKS='heroku-18 ...'] [ENV_FILE=...]")
 endif
 	@echo "Using: RUNTIMES='$(RUNTIMES)' STACKS='$(STACKS)' ENV_FILE='$(ENV_FILE)'"
 	@echo
-	@docker build --pull -f $(shell pwd)/builds/heroku-18.Dockerfile -t python-buildenv-heroku-18 .
+	@set -eu; for stack in $(STACKS); do \
-	@echo
+		$(MAKE) builder-image STACK=$${stack}; \
-	@echo "Usage..."
+		for runtime in $(RUNTIMES); do \
-	@echo
+			echo "Generating/deploying $${runtime} for $${stack}..."; \
-	@echo "  $$ export AWS_ACCESS_KEY_ID=foo AWS_SECRET_ACCESS_KEY=bar  # Optional unless deploying"
+			echo; \
-	@echo "  $$ bob build runtimes/python-2.7.13"
+			docker run --rm -it --env-file="$(ENV_FILE)" "$(BUILDER_IMAGE_PREFIX)-$${stack}" bob deploy "runtimes/$${runtime}"; \
-	@echo "  $$ bob deploy runtimes/python-2.7.13"
+			echo; \
-	@echo
+		done; \
-	@docker run -it --rm python-buildenv-heroku-18
+	done
 tools:
 	git clone https://github.com/kennethreitz/pip-pop.git
 	mv pip-pop/bin/* vendor/pip-pop/
 	rm -fr pip-pop
@@ -1,27 +1,5 @@
 This buildpack includes some vendorized packages to ease installation.
 jq license
 ----------
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 shunit2 license
 ---------------
@@ -85,28 +63,3 @@ The Free Software Foundation may publish revised and/or new versions of the GNU
 Each version is given a distinguishing version number. If the Library as you received it specifies that a certain numbered version of the GNU Lesser General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that published version or of any later version published by the Free Software Foundation. If the Library as you received it does not specify a version number of the GNU Lesser General Public License, you may choose any version of the GNU Lesser General Public License ever published by the Free Software Foundation.
 If the Library as you received it specifies that a proxy can decide whether future versions of the GNU Lesser General Public License shall apply, that proxy's public statement of acceptance of any version is permanent authorization for you to choose that version for the Library.
 pip-pop license
 ---------------
 The MIT License (MIT)
 Copyright (c) 2014 Kenneth Reitz.
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
@@ -26,7 +26,7 @@ remote: Compressing source files... done.
 remote: Building source:
 remote:
 remote: -----> Python app detected
-remote: -----> Installing python-3.7.4
+remote: -----> Installing python
 remote: -----> Installing pip
 remote: -----> Installing SQLite3
 remote: -----> Installing requirements with pip
@@ -44,7 +44,7 @@ A `requirements.txt` must be present at the root of your application's repositor
 To specify your python version, you also need a `runtime.txt` file - unless you are using the default Python runtime version.
-Current default Python Runtime: Python 3.6.9
+Current default Python Runtime: Python 3.6.12
 Alternatively, you can provide a `setup.py` file, or a `Pipfile`.
 Using `pipenv` will generate `runtime.txt` at build time if one of the field `python_version` or `python_full_version` is specified in the `requires` section of your `Pipfile`.
@@ -62,9 +62,10 @@ Specify a Python Runtime
 Supported runtime options include:
- `python-3.8.5`
+- `python-3.9.0`
- `python-3.7.8`
+- `python-3.8.7`
- `python-3.6.11`
+- `python-3.7.9`
 - `python-3.6.12`
 - `python-2.7.18`
 ## Tests
@@ -15,10 +15,8 @@
 # Fail fast and fail hard.
 set -eo pipefail
-# Boostrap the Buildpack Standard Library.
+# Used by buildpack-stdlib's metrics features.
-# Disable unused env var warning since shellcheck doesn't know about the stdlib.
+export BPLOG_PREFIX="buildpack.python"
 # shellcheck disable=2034
 BPLOG_PREFIX="buildpack.python"
 export BUILDPACK_LOG_FILE=${BUILDPACK_LOG_FILE:-/dev/null}
 [ "$BUILDPACK_XTRACE" ] && set -o xtrace
@@ -37,23 +35,19 @@ ENV_DIR=$3
 # Export Path variables, for use in sub-scripts.
 export BUILD_DIR CACHE_DIR ENV_DIR
-# Set the Buildpack's internet target for downloading Python distributions.
+# Set the base URL for downloading buildpack assets like Python runtimes.
-# The user can provide BUILDPACK_VENDOR_URL to specify a custom target.
+# The user can provide BUILDPACK_S3_BASE_URL to specify a custom target.
 # Note: this is designed for non-Heroku use, as it does not use the user-provided
 # environment variable mechanism (the ENV_DIR).
-VENDOR_URL="https://lang-python.s3.amazonaws.com/$STACK"
+S3_BASE_URL="${BUILDPACK_S3_BASE_URL:-"https://heroku-buildpack-python.s3.amazonaws.com"}"
-if [[ -n ${BUILDPACK_VENDOR_URL:-} ]]; then
+# This has to be exported since it's used by the geo-libs step which is run in a subshell.
    VENDOR_URL="$BUILDPACK_VENDOR_URL"
 elif [[ -n ${USE_STAGING_BINARIES} ]]; then
    VENDOR_URL="$USE_STAGING_BINARIES/$STACK"
 fi
 export VENDOR_URL
 # Default Python Versions
 # shellcheck source=bin/default_pythons
 source "$BIN_DIR/default_pythons"
 # Supported Python Branches
 PY39="python-3.9"
 PY38="python-3.8"
 PY37="python-3.7"
 PY36="python-3.6"
@@ -64,7 +58,8 @@ PYPY27="pypy2.7"
 PYPY36="pypy3.6"
 # Which stack is used (for binary downloading), if none is provided (e.g. outside of Heroku)?
-DEFAULT_PYTHON_STACK="cedar-14"
+# TODO: Remove this and require that STACK be set explicitly.
 DEFAULT_PYTHON_STACK="heroku-18"
 # Common Problem Warnings:
 # This section creates a temporary file in which to stick the output of `pip install`.
@@ -73,24 +68,18 @@ DEFAULT_PYTHON_STACK="cedar-14"
 WARNINGS_LOG=$(mktemp)
 RECOMMENDED_PYTHON_VERSION=$DEFAULT_PYTHON_VERSION
-# The buildpack ships with a few executable tools (e.g. pip-grep, etc).
+# The buildpack ships with a few executable tools.
 # This installs them into the path, so we can execute them directly.
-export PATH=$PATH:$ROOT_DIR/vendor/:$ROOT_DIR/vendor/pip-pop
+export PATH=$PATH:$ROOT_DIR/vendor/
 # Set environment variables if they weren't set by the platform.
 # Note: this is legacy, for a deprecated build system known as Anvil.
 # This can likely be removed, with caution.
 [ ! "$SLUG_ID" ] && SLUG_ID="defaultslug"
 [ ! "$REQUEST_ID" ] && REQUEST_ID=$SLUG_ID
 [ ! "$STACK" ] && STACK=$DEFAULT_PYTHON_STACK
 # Sanitize externally-provided environment variables:
 # The following environment variables are either problematic or simply unneccessary
 # for the buildpack to have knowledge of, so we unset them, to keep the environment
 # as clean and pristine as possible.
-unset GIT_DIR PYTHONHOME PYTHONPATH
+unset PYTHONHOME PYTHONPATH
 unset RECEIVE_DATA RUN_KEY BUILD_INFO DEPLOY LOG_TOKEN
 unset CYTOKINE_LOG_FILE GEM_PATH
 # Import the utils script, which contains helper functions used throughout the buildpack.
 # shellcheck source=bin/utils
@@ -101,6 +90,33 @@ source "$BIN_DIR/utils"
 # shellcheck source=bin/warnings
 source "$BIN_DIR/warnings"
 if [[ "${STACK}" == "cedar-14" ]]; then
  mcount "failure.unsupported.cedar-14"
  puts-warn "The Cedar-14 stack is no longer supported by the latest release of this buildpack."
  puts-warn
  puts-warn "Please switch to the Cedar-14 support branch by using this buildpack URL:"
  puts-warn "https://github.com/heroku/heroku-buildpack-python#cedar-14"
  puts-warn
  puts-warn "For instructions on how to change the buildpacks used by an app, see:"
  puts-warn "https://devcenter.heroku.com/articles/buildpacks#setting-a-buildpack-on-an-application"
  exit 1
 fi
 if [[ -f "${ENV_DIR}/BUILD_WITH_GEO_LIBRARIES" ]]; then
  mcount "failure.unsupported.BUILD_WITH_GEO_LIBRARIES"
  puts-warn "The Python buildpack's legacy BUILD_WITH_GEO_LIBRARIES functonality is"
  puts-warn "no longer supported:"
  puts-warn "https://devcenter.heroku.com/changelog-items/1947"
  puts-warn
  puts-warn "To continue to use GDAL, GEOS or PROJ support, see the migration guide:"
  puts-warn "https://help.heroku.com/D5INLB1A/python-s-build_with_geo_libraries-legacy-feature-is-no-longer-supported"
  puts-warn
  puts-warn "Or if you no longer need those libraries, this message can be hidden by"
  puts-warn "unsetting the BUILD_WITH_GEO_LIBRARIES environment variable, using:"
  puts-warn "heroku config:unset BUILD_WITH_GEO_LIBRARIES"
  exit 1
 fi
 # Make the directory in which we will create symlinks from the temporary build directory
 # to `/app`.
 # Symlinks are required, since Python is not a portable installation.
@@ -129,8 +145,9 @@ export PYTHONUNBUFFERED=1
 # Set the locale to a well-known and expected standard.
 export LANG=en_US.UTF-8
 # `~/.heroku/vendor` is an place where the buildpack may stick pre-build binaries for known
-# C dependencies (e.g. libmemcached on cedar-14). This section configures Python (GCC, more specifically)
+# C dependencies. This section configures Python (GCC, more specifically)
 # and pip to automatically include these paths when building binaries.
 # TODO: Stop adding .heroku/vendor here now that the buildpack no longer vendors anything.
 export C_INCLUDE_PATH=/app/.heroku/vendor/include:/app/.heroku/python/include:$C_INCLUDE_PATH
 export CPLUS_INCLUDE_PATH=/app/.heroku/vendor/include:/app/.heroku/python/include:$CPLUS_INCLUDE_PATH
 export LIBRARY_PATH=/app/.heroku/vendor/lib:/app/.heroku/python/lib:$LIBRARY_PATH
@@ -170,8 +187,6 @@ cp -R "$CACHE_DIR/.heroku/python-stack" .heroku/ &> /dev/null || true
 cp -R "$CACHE_DIR/.heroku/python-version" .heroku/ &> /dev/null || true
 # A plain text file which contains the current sqlite3 version being used (used for cache busting).
 cp -R "$CACHE_DIR/.heroku/python-sqlite3-version" .heroku/ &> /dev/null || true
 # Any pre-compiled binaries, provided by the buildpack.
 cp -R "$CACHE_DIR/.heroku/vendor" .heroku/ &> /dev/null || true
 # "editable" installations of code repositories, via pip or pipenv.
 if [[ -d "$CACHE_DIR/.heroku/src" ]]; then
  cp -R "$CACHE_DIR/.heroku/src" .heroku/ &> /dev/null || true
@@ -189,7 +204,7 @@ source "$BIN_DIR/steps/hooks/pre_compile"
 # continue to use that version of Python in perpituity (warnings will be raised if
 # they are out–of–date).
 if [ -f "$CACHE_DIR/.heroku/python-version" ]; then
-  DEFAULT_PYTHON_VERSION=$(cat "$CACHE_DIR/.heroku/python-version")
+  CACHED_PYTHON_VERSION=$(cat "$CACHE_DIR/.heroku/python-version")
 fi
 # We didn't always record the stack version. This code is in place because of that.
@@ -206,9 +221,14 @@ fi
 # shellcheck source=bin/steps/pipenv-python-version
 source "$BIN_DIR/steps/pipenv-python-version"
-# If no runtime was provided by the user, assume the default Python runtime version.
+if [[ -f runtime.txt ]]; then
-if [ ! -f runtime.txt ]; then
+  mcount "version.reason.python.specified"
-  echo "$DEFAULT_PYTHON_VERSION" > runtime.txt
+elif [[ -n "${CACHED_PYTHON_VERSION:-}" ]]; then
  mcount "version.reason.python.cached"
  echo "${CACHED_PYTHON_VERSION}" > runtime.txt
 else
  mcount "version.reason.python.default"
  echo "${DEFAULT_PYTHON_VERSION}" > runtime.txt
 fi
 # Create the directory for .profile.d, if it doesn't exist.
@@ -252,27 +272,6 @@ fi
 # shellcheck source=bin/steps/eggpath-fix
 source "$BIN_DIR/steps/eggpath-fix"
 # Mercurial support.
 # If a customer appears to be using mercurial for dependency resolution, we install it first.
 # Note: this only applies to pip, not pipenv. This can likely be removed, over time. Measure it first.
 # shellcheck source=bin/steps/mercurial
 source "$BIN_DIR/steps/mercurial"
 # Pylibmc support.
 # On cedar-14, libmemcached was not available. The buildpack provides its own version, instead.
 # shellcheck source=bin/steps/pylibmc
 source "$BIN_DIR/steps/pylibmc"
 # Support for Geo libraries. This is deprecated functionality, only functional on cedar-14.
 # It is undocumented.
 # shellcheck source=bin/steps/geo-libs
 sub_env "$BIN_DIR/steps/geo-libs"
 # GDAL support.
 # This is part of the Geo support.
 # shellcheck source=bin/steps/gdal
 source "$BIN_DIR/steps/gdal"
 # SQLite3 support.
 # This sets up and installs sqlite3 dev headers and the sqlite3 binary but not the
 # libsqlite3-0 library since that exists on the stack image.
@@ -304,7 +303,7 @@ mtime "nltk.download.time" "${start}"
 # and copying it into the proper place (the logical place to do this was early, but it must be done here).
 # In CI, $BUILD_DIR is /app.
 if [[ ! "$BUILD_DIR" == "/app" ]]; then
-  rm -fr "$BUILD_DIR/.heroku/src"
+  rm -rf "$BUILD_DIR/.heroku/src"
  deep-cp /app/.heroku/src "$BUILD_DIR/.heroku/src"
 fi
@@ -370,7 +369,6 @@ mkdir -p "$CACHE_DIR/.heroku"
 cp -R .heroku/python "$CACHE_DIR/.heroku/"
 cp -R .heroku/python-version "$CACHE_DIR/.heroku/"
 cp -R .heroku/python-stack "$CACHE_DIR/.heroku/" &> /dev/null || true
 cp -R .heroku/vendor "$CACHE_DIR/.heroku/" &> /dev/null || true
 if [[ -d .heroku/src ]]; then
  cp -R .heroku/src "$CACHE_DIR/.heroku/" &> /dev/null || true
 fi
@@ -5,12 +5,13 @@
 # the env vars to subprocesses.
 # shellcheck disable=2034
-DEFAULT_PYTHON_VERSION="python-3.6.11"
+DEFAULT_PYTHON_VERSION="python-3.6.12"
-LATEST_38="python-3.8.5"
+LATEST_39="python-3.9.0"
-LATEST_37="python-3.7.8"
+LATEST_38="python-3.8.7"
-LATEST_36="python-3.6.11"
+LATEST_37="python-3.7.9"
-LATEST_35="python-3.5.9"
+LATEST_36="python-3.6.12"
 LATEST_35="python-3.5.10"
 LATEST_34="python-3.4.10"
 LATEST_27="python-2.7.18"
-PYPY_36="pypy3.6-7.3.1"
+LATEST_PYPY_36="pypy3.6-7.3.2"
-PYPY_27="pypy2.7-7.3.1"
+LATEST_PYPY_27="pypy2.7-7.3.2"
@@ -20,8 +20,8 @@ MANAGE_FILE=${MANAGE_FILE:-fakepath}
 # Legacy file-based support for $DISABLE_COLLECTSTATIC
 [ -f .heroku/collectstatic_disabled ] && DISABLE_COLLECTSTATIC=1
-# Ensure that Django is explicitly specified in requirements.txt
+# Ensure that Django is actually installed.
-sp-grep -s django && DJANGO_INSTALLED=1
+is_module_available 'django' && DJANGO_INSTALLED=1
 if [ ! "$DISABLE_COLLECTSTATIC" ] && [ -f "$MANAGE_FILE" ] && [ "$DJANGO_INSTALLED" ]; then
@@ -1,38 +0,0 @@
 #!/usr/bin/env bash
 # This script serves as the GDAL build step of the
 # [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
 # compiler.
 #
 # A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
 # adapter between a Python application and Heroku's runtime.
 #
 # This script is invoked by [`bin/compile`](/).
 # The location of the pre-compiled cryptography binary.
 VENDORED_GDAL="${VENDOR_URL}/libraries/vendor/gdal.tar.gz"
 PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
 # Syntax sugar.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 # If GDAL exists within requirements, use vendored gdal.
 if (pip-grep -s requirements.txt GDAL gdal pygdal &> /dev/null) then
  if [ ! -f ".heroku/vendor/bin/gdalserver" ]; then
    puts-warn "The vendored GDAL package in the Heroku Python Buildpack now deprecated."
    puts-warn "To enable GDAL use an alternative buildpack is available here - https://github.com/heroku/heroku-geo-buildpack"
    echo "-----> Noticed GDAL. Bootstrapping gdal."
    mkdir -p .heroku/vendor
    # Download and extract cryptography into target vendor directory.
    curl "$VENDORED_GDAL" -s | tar zxv -C .heroku/vendor &> /dev/null
    mcount "steps.vendor.gdal"
  fi
  GDAL=$(pwd)/vendor
  export GDAL
 fi
@@ -1,55 +0,0 @@
 #!/usr/bin/env bash
 # This script serves as the GDAL build step of the
 # [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
 # compiler.
 #
 # A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
 # adapter between a Python application and Heroku's runtime.
 #
 # This script is invoked by [`bin/compile`](/).
 # The location of the pre-compiled cryptography binary.
 VENDORED_GDAL="${VENDOR_URL}/libraries/vendor/gdal.tar.gz"
 VENDORED_GEOS="${VENDOR_URL}/libraries/vendor/geos.tar.gz"
 VENDORED_PROJ="${VENDOR_URL}/libraries/vendor/proj.tar.gz"
 PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
 # Syntax sugar.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 # If GDAL exists within requirements, use vendored gdal.
 if [[ "$BUILD_WITH_GEO_LIBRARIES" ]]; then
  mcount "buildvar.BUILD_WITH_GEO_LIBRARIES"
  puts-warn "The GDAL, GEOS and PROJ binaries and BUILD_WITH_GEO_LIBRARIES functonality are now deprecated."
  puts-warn "An alternative buildpack to enable GDAL, GEOS and PROJ use is available here - https://github.com/heroku/heroku-geo-buildpack"
  if [ ! -f ".heroku/vendor/bin/proj" ]; then
    echo "-----> Bootstrapping gdal, geos, proj."
    mkdir -p .heroku/vendor
    # Download and extract cryptography into target vendor directory.
    curl "$VENDORED_GDAL" -s | tar zxv -C .heroku/vendor &> /dev/null
    curl "$VENDORED_GEOS" -s | tar zxv -C .heroku/vendor &> /dev/null
    curl "$VENDORED_PROJ" -s | tar zxv -C .heroku/vendor &> /dev/null
    mcount "steps.vendor.geo_libs"
    # Copy libjasper from build image to slug.
    if [[ "$STACK" == "heroku-16" ]]; then
      cp /usr/lib/x86_64-linux-gnu/libjasper.so* ".heroku/vendor/lib/."
      mcount "steps.vendor.libjasper"
    fi
  fi
  GDAL=$(pwd)/vendor
  export GDAL
  # set path for post_compile hooks
  export GDAL_LIBRARY_PATH="$BUILD_DIR/.heroku/vendor/lib/libgdal.so"
  export GEOS_LIBRARY_PATH="$BUILD_DIR/.heroku/vendor/lib/libgeos_c.so"
  # set path for runtime environmeht
  set_env GDAL_LIBRARY_PATH "/app/.heroku/vendor/lib/libgdal.so"
  set_env GEOS_LIBRARY_PATH "/app/.heroku/vendor/lib/libgeos_c.so"
 fi
@@ -1,9 +0,0 @@
 #!/usr/bin/env bash
 # Install Mercurial if it appears to be required.
 if [[ -f "requirements.txt" ]]; then
 	if (grep -Fiq "hg+" requirements.txt) then
 		/app/.heroku/python/bin/pip install  mercurial | cleanup | indent
 		mcount "steps.mercurial"
 	fi
 fi
@@ -14,7 +14,7 @@
 source "$BIN_DIR/utils"
 # Check that nltk was installed by pip, otherwise obviously not needed
-if sp-grep -s nltk; then
+if is_module_available 'nltk'; then
    puts-step "Downloading NLTK corpora…"
    nltk_packages_definition="$BUILD_DIR/nltk.txt"
@@ -1,28 +0,0 @@
 #!/usr/bin/env bash
 set +e
 # Install dependencies with Pip.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 if [ ! "$SKIP_PIP_INSTALL" ]; then
  if [[ -f .heroku/python/requirements-declared.txt ]]; then
    cp .heroku/python/requirements-declared.txt requirements-declared.txt
    if ! pip-diff --stale requirements-declared.txt requirements.txt --exclude setuptools pip wheel > .heroku/python/requirements-stale.txt; then
      mcount "failure.bad-requirements"
    fi
    rm -fr requirements-declared.txt
    if [[ -s .heroku/python/requirements-stale.txt ]]; then
      puts-step "Uninstalling stale dependencies"
      /app/.heroku/python/bin/pip uninstall -r .heroku/python/requirements-stale.txt -y --exists-action=w --disable-pip-version-check | cleanup | indent
    fi
  fi
 fi
 set -e
@@ -9,10 +9,7 @@ set -e
 if [[ -f Pipfile.lock ]]; then
    if [[ -f .heroku/python/Pipfile.lock.sha256 ]]; then
        if [[ $(openssl dgst -sha256 Pipfile.lock) == $(cat .heroku/python/Pipfile.lock.sha256) ]]; then
-            # Measure that we're using Pipenv.
+            # Don't skip installation if there are git deps.
            mcount "tool.pipenv"
            # Don't skip installation of there are git deps.
            if ! grep -q 'git' Pipfile.lock; then
                echo "Skipping installation, as Pipfile.lock hasn't changed since last deploy." | indent
@@ -72,7 +69,6 @@ if [ ! "$SKIP_PIPENV_INSTALL" ]; then
        else
            pipenv-to-pip Pipfile.lock > requirements.txt
            "$BIN_DIR/steps/pip-uninstall"
            cp requirements.txt .heroku/python/requirements-declared.txt
            openssl dgst -sha256 Pipfile.lock > .heroku/python/Pipfile.lock.sha256
@@ -30,6 +30,9 @@ if [[ -f $BUILD_DIR/Pipfile ]]; then
                if [ "$PYTHON" = 3.8 ]; then
                    echo "$LATEST_38" > "$BUILD_DIR/runtime.txt"
                fi
                if [ "$PYTHON" = 3.9 ]; then
                    echo "$LATEST_39" > "$BUILD_DIR/runtime.txt"
                fi
            fi
@@ -1,37 +0,0 @@
 #!/usr/bin/env bash
 # This script serves as the Pylibmc build step of the
 # [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
 # compiler.
 #
 # A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
 # adapter between a Python application and Heroku's runtime.
 #
 # This script is invoked by [`bin/compile`](/).
 if [[ "$STACK" != "cedar-14" ]]; then
    # libmemcached is pre-installed in the stack image so there is no need to vendor it.
    return 0
 fi
 # The location of the pre-compiled libmemcached binary.
 VENDORED_MEMCACHED="${VENDOR_URL}/libraries/vendor/libmemcache.tar.gz"
 # Syntax sugar.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 # If pylibmc exists within requirements, use vendored libmemcached.
 if (pip-grep -s requirements.txt pylibmc &> /dev/null) then
  if [ ! -d ".heroku/vendor/lib/sasl2" ]; then
    echo "-----> Noticed pylibmc. Bootstrapping libmemcached."
    mkdir -p .heroku/vendor
    # Download and extract libmemcached into target vendor directory.
    curl "$VENDORED_MEMCACHED" -s | tar zxv -C .heroku/vendor &> /dev/null
    mcount "steps.vendor.pylibmc"
  fi
  LIBMEMCACHED=$(pwd)/vendor
  export LIBMEMCACHED
 fi
@@ -5,9 +5,10 @@ runtime-fixer runtime.txt
 PYTHON_VERSION=$(cat runtime.txt)
 # The location of the pre-compiled python binary.
-VENDORED_PYTHON="${VENDOR_URL}/runtimes/$PYTHON_VERSION.tar.gz"
+VENDORED_PYTHON="${S3_BASE_URL}/${STACK}/runtimes/${PYTHON_VERSION}.tar.gz"
 SECURITY_UPDATE="Python has released a security update! Please consider upgrading to"
 SECURITY_UPDATE_PYPY="The PyPy project has released a security update! Please consider upgrading to"
 ONLY_SUPPORTED_2_VERSION="Only the latest version of Python 2 is supported on the platform. Please consider upgrading to"
@@ -15,6 +16,12 @@ PYTHON_2_EOL_UPDATE="Python 2 has reached it's community EOL. Upgrade your Pytho
 # check if runtime exists
 if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
  if [[ "$PYTHON_VERSION" == $PY39* ]]; then
    if [ "$PYTHON_VERSION" != "$LATEST_39" ]; then
      puts-warn "$SECURITY_UPDATE" "$LATEST_39"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
    fi
  fi
  if [[ "$PYTHON_VERSION" == $PY38* ]]; then
    # do things to alert the user of security release available
    if [ "$PYTHON_VERSION" != "$LATEST_38" ]; then
@@ -51,11 +58,9 @@ if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
    fi
  fi
  if [[ "$PYTHON_VERSION" == $PY27* ]]; then
    # security update note
    if [[ "$(date "+%Y")" -gt "2019" ]]; then
    puts-warn "$PYTHON_2_EOL_UPDATE"
    echo "       Learn More: https://devcenter.heroku.com/articles/python-2-7-eol-faq"
-    fi
+    # security update note
    if [ "$PYTHON_VERSION" != "$LATEST_27" ]; then
      puts-warn "$ONLY_SUPPORTED_2_VERSION" "$LATEST_27"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
@@ -63,15 +68,15 @@ if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
  fi
  if [[ "$PYTHON_VERSION" == $PYPY27* ]]; then
    # security update note
-    if [ "$PYTHON_VERSION" != "$PYPY_27" ]; then
+    if [ "$PYTHON_VERSION" != "$LATEST_PYPY_27" ]; then
-      puts-warn "Could not find that Pypy version. Did you mean" "${PYPY_27}?"
+      puts-warn "$SECURITY_UPDATE_PYPY" "$LATEST_PYPY_27"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
    fi
  fi
  if [[ "$PYTHON_VERSION" == $PYPY36* ]]; then
    # security update note
-    if [ "$PYTHON_VERSION" != "$PYPY_36" ]; then
+    if [ "$PYTHON_VERSION" != "$LATEST_PYPY_36" ]; then
-      puts-warn "Could not find that Pypy version. Did you mean" "${PYPY_36}?"
+      puts-warn "$SECURITY_UPDATE_PYPY" "$LATEST_PYPY_36"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
    fi
  fi
@@ -81,15 +86,17 @@ else
  exit 1
 fi
 mcount "version.python.${PYTHON_VERSION}"
 if [[ "$STACK" != "$CACHED_PYTHON_STACK" ]]; then
    puts-step "Stack has changed from $CACHED_PYTHON_STACK to $STACK, clearing cache"
-    rm -fr .heroku/python-stack .heroku/python-version .heroku/python .heroku/vendor .heroku/python .heroku/python-sqlite3-version
+    rm -rf .heroku/python-stack .heroku/python-version .heroku/python .heroku/vendor .heroku/python .heroku/python-sqlite3-version
 fi
 if [ -f .heroku/python-version ]; then
  if [ ! "$(cat .heroku/python-version)" = "$PYTHON_VERSION" ]; then
      puts-step "Found $(cat .heroku/python-version), removing"
-      rm -fr .heroku/python
+      rm -rf .heroku/python
  else
    SKIP_INSTALL=1
  fi
@@ -120,8 +127,6 @@ if [ ! "$SKIP_INSTALL" ]; then
    # Prepare destination directory.
    mkdir -p .heroku/python
    mcount "version.python.$PYTHON_VERSION"
    if ! curl "${VENDORED_PYTHON}" -s | tar zxv -C .heroku/python &> /dev/null; then
      puts-warn "Requested runtime ($PYTHON_VERSION) is not available for this stack ($STACK)."
      puts-warn "Aborting.  More info: https://devcenter.heroku.com/articles/python-support"
@@ -161,7 +166,7 @@ fi
 # Instead, we use the pip wheel to install itself, using the method described here:
 # https://github.com/pypa/pip/issues/2351#issuecomment-69994524
 PIP_WHEEL_FILENAME="pip-${PIP_VERSION}-py2.py3-none-any.whl"
-PIP_WHEEL_URL="https://lang-python.s3.amazonaws.com/common/${PIP_WHEEL_FILENAME}"
+PIP_WHEEL_URL="${S3_BASE_URL}/common/${PIP_WHEEL_FILENAME}"
 PIP_WHEEL="${TMPDIR:-/tmp}/${PIP_WHEEL_FILENAME}"
 if ! curl -sSf "${PIP_WHEEL_URL}" -o "$PIP_WHEEL"; then
@@ -2,12 +2,13 @@
 shopt -s extglob
 shopt -s nullglob
-# The standard library.
+# This is necessary since this script is sometimes sourced from
-if [[ ! -f  /tmp/stdlib.sh ]]; then
+# subshells that don't have the variables from bin/compile.
-  curl --retry 3 -s https://lang-common.s3.amazonaws.com/buildpack-stdlib/v8/stdlib.sh > /tmp/stdlib.sh
+# Remove this once we no longer wrap all the things in `sub_env`.
-fi
+BIN_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
-# shellcheck source=/dev/null
+ROOT_DIR=$(dirname "${BIN_DIR}")
-source /tmp/stdlib.sh
+# shellcheck source=vendor/buildpack-stdlib_v8.sh
 source "${ROOT_DIR}/vendor/buildpack-stdlib_v8.sh"
 if [ "$(uname)" == Darwin ]; then
    sed() { command sed -l "$@"; }
@@ -95,3 +96,11 @@ python_sqlite3_check() {
  ( python2_check "$VERSION" && version_gte "$VERSION" "$MIN_PYTHON_2" ) \
    || ( python3_check "$VERSION" && version_gte "$VERSION" "$MIN_PYTHON_3" )
 }
 is_module_available() {
  # Returns 0 is the specified module exists, otherwise returns 1.
  # Uses pkgutil rather than pkg_resources or pip's CLI, since pkgutil exists
  # in the stdlib, and doesn't depend on the choice of package manager.
  local module_name="${1}"
  python -c "import sys, pkgutil; sys.exit(0 if pkgutil.find_loader('${module_name}') else 1)"
 }
@@ -12,16 +12,6 @@ old-platform() {
  fi
 }
 pylibmc-missing() {
  if grep -qi 'fatal error: libmemcached/memcached.h: No such file or directory' "$WARNINGS_LOG"; then
    echo
    puts-warn "Hello! There was a problem with your build related to libmemcache."
    puts-warn "The Python library 'pylibmc' must be explicitly specified in 'requirements.txt' in order to build correctly."
    puts-warn "Once you do that, everything should work as expected.   -- Much Love, Heroku."
    mcount 'warnings.libmemcache'
  fi
 }
 scipy-included() {
  if grep -qi 'running setup.py install for scipy' "$WARNINGS_LOG"; then
    echo
@@ -56,11 +46,22 @@ six-included() {
  fi
 }
 gdal-missing() {
  if grep -qi 'Could not find gdal-config' "$WARNINGS_LOG"; then
    mcount 'warnings.gdal'
    echo
    puts-warn "Hello! Package installation failed since the GDAL library was not found."
    puts-warn "For GDAL, GEOS and PROJ support, use the Geo buildpack alongside the Python buildpack:"
    puts-warn "https://github.com/heroku/heroku-geo-buildpack"
    puts-warn "  -- Much Love, Heroku."
  fi
 }
 show-warnings() {
  old-platform
  pylibmc-missing
  scipy-included
  distribute-included
  six-included
  gdal-missing
 }
@@ -1,57 +1,80 @@
 # Python Buildpack Binaries
-## Building the Docker Images
+The binaries for this buildpack are built in Docker containers based on the Heroku stack image.
 **After every change to your formulae, perform the following** from the root of the Git repository (not from `builds/`) to rebuild the images for each stack:
    $ docker build --pull --tag heroku-python-build-cedar-14 --file $(pwd)/builds/cedar-14.Dockerfile .
    $ docker build --pull --tag heroku-python-build-heroku-16 --file $(pwd)/builds/heroku-16.Dockerfile .
    $ docker build --pull --tag heroku-python-build-heroku-18 --file $(pwd)/builds/heroku-18.Dockerfile .
 ## Using the Image
 You can e.g. `bash` into each of the images you built using their tag:
    docker run --rm -ti heroku-python-build-cedar-14 bash
    docker run --rm -ti heroku-python-build-heroku-16 bash
    docker run --rm -ti heroku-python-build-heroku-18 bash
 You then have a shell where you can run `bob build`, `bob deploy`, and so forth. You can of course also invoke these programs directly with `docker run`:
    docker run --rm -ti heroku-python-build-heroku-18 bob build runtimes/python-2.7.15
 In order to `bob deploy`, AWS credentials must be set up, as well as name and prefix of your custom S3 bucket (unless you're deploying to the Heroku production buckets that are pre-defined in each `Dockerfile`); see next section for details.
 ## Configuration
-File `dockerenv.default` contains a list of required env vars; most of these have default values defined in `Dockerfile`. You can copy this file to a location outside the buildpack and modify it with the values you desire and pass its location with `--env-file`, or pass the env vars to `docker run` using `--env`.
+In order to publish binaries AWS credentials must be passed to the build container.
 If you are testing only the build (ie: `bob build`), these are optional.
-Out of the box, each `Dockerfile` has the correct values predefined for `S3_BUCKET`, `S3_PREFIX`, and `S3_REGION`. If you're building your own packages, you'll likely want to change `S3_BUCKET` and `S3_PREFIX` to match your info. Instead of setting `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` into that file, you may also pass them to `docker run` through the environment, or explicitly using `--env`, in order to prevent accidental commits of credentials.
+In addition, unless you are building the official binaries for Heroku (which use the defaults
 specified in each `Dockerfile`), you will need to override `S3_BUCKET` and `S3_PREFIX` to
 match your own S3 bucket/use case.
-### Passing AWS credentials to the container
+If you only need to set AWS credentials, you can do so by setting the environment variables
 `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` before calling the make commands.
-If you want to deploy packages and thus need to pass `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY`, you can either pass them explicitly, through your environment, or through an env file.
+For example:
 #### Passing credentials explicitly
    docker run --rm -ti -e AWS_ACCESS_KEY_ID=... -e AWS_SECRET_ACCESS_KEY=... heroku-python-build-heroku-18 bash
 #### Passing credentials through  the environment
 The two environment variables `AWS_ACCESS_KEY_ID`and `AWS_SECRET_ACCESS_KEY` are defined in `builds/dockerenv.default`, without values. This will cause Docker to "forward" values for these variables from the current environment, so you can pass them in:
    AWS_ACCESS_KEY_ID=... AWS_SECRET_ACCESS_KEY=... docker run --rm -ti --env-file=builds/dockerenv.default heroku-python-build-heroku-18 bash
 or
 ```bash
 set +o history # Disable bash history
 export AWS_ACCESS_KEY_ID=...
 export AWS_SECRET_ACCESS_KEY=...
-    docker run --rm -ti --env-file=builds/dockerenv.default heroku-python-build-heroku-18 bash
+set -o history # Re-enable bash history
 make ...
 ```
-#### Passing credentials through a separate env file
+If you need to override the default S3 bucket, or would prefer not to use credentials via
 environment variables, then you need to instead use a Docker env file like so:
-This method is the easiest for users who want to build packages in their own S3 bucket, as they will have to adjust the `S3_BUCKET` and `S3_PREFIX` environment variable values anyway from their default values.
+1. Copy the `builds/dockerenv.default` env file to a location outside the buildpack repository.
 2. Edit the new file, adding at a minimum the values for the variables
   `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` (see Docker
   [env-file documentation](https://docs.docker.com/engine/reference/commandline/run/#set-environment-variables--e---env---env-file)).
 3. Pass the path of the file to the make commands using `ENV_FILE`. For example:
-For this method, it is important to keep the credentials file in a location outside the buildpack, so that your credentials aren't accidentally committed. Copy `builds/dockerenv.default` **to a safe location outside the buildpack directory**, and insert your values for `AWS_ACCESS_KEY_ID`and `AWS_SECRET_ACCESS_KEY`.
+   ```bash
   make ... ENV_FILE=~/.dockerenv.python-buildpack
   ```
-    docker run --rm -ti --env-file=../SOMEPATHOUTSIDE/s3.env heroku-python-build-heroku-18 bash
+## Launching an interactive build environment
 To start an interactive version of the build environment (ideal for development) use the
 `buildenv` make target, passing in the desired `STACK` name. For example:
 ```bash
 make buildenv STACK=heroku-18
 ```
 This will create the builder docker image based on the latest image for that stack, and
 then start a bash shell where you can run `bob build`, `bob deploy`, and so forth.
 The `builds/` directory is bind-mounted into the running container, so local build formula
 changes will appear there immediately without the need to rebuild the image.
 ## Bulk deploying runtimes
 When a new Python version is released, binaries have to be generated for multiple stacks.
 To automate this, use the `deploy-runtimes` make target, which will ensure the builder
 image is up to date, and then run `bob deploy` for each runtime-stack combination.
 The build formula name(s) are passed using `RUNTIMES`, like so:
 ```bash
 make deploy-runtimes RUNTIMES='python-X.Y.Z'
 ```
 By default this will deploy to all supported stacks (see `STACKS` in `Makefile`),
 but this can be overridden using `STACKS`:
 ```bash
 make deploy-runtimes RUNTIMES='python-X.Y.Z' STACKS='heroku-16 heroku-18'
 ```
 Multiple runtimes can also be specified (useful for when adding a new stack), like so:
 ```bash
 make deploy-runtimes RUNTIMES='python-A.B.C python-X.Y.Z' STACKS='heroku-20'
 ```
 Note: Both `RUNTIMES` and `STACKS` are space delimited.
@@ -1,15 +0,0 @@
 FROM heroku/cedar:14
 WORKDIR /app
 ENV WORKSPACE_DIR="/app/builds" \
    S3_BUCKET="lang-python" \
    S3_PREFIX="cedar-14/" \
    DEBIAN_FRONTEND=noninteractive \
    STACK="cedar-14"
 RUN apt-get update && apt-get install -y python-pip libsqlite3-dev realpath && rm -rf /var/lib/apt/lists/*
 COPY requirements.txt /app/
 RUN pip install -r /app/requirements.txt
 COPY . /app
@@ -1,5 +1,8 @@
 # Since no values are specified here, these variables will be read from the environment at run time:
 # https://docs.docker.com/engine/reference/commandline/run/#set-environment-variables--e---env---env-file
 AWS_ACCESS_KEY_ID
 AWS_SECRET_ACCESS_KEY
-S3_BUCKET
+
-S3_PREFIX
+# Uncomment these if you need to override the default S3 bucket and/or path prefixes.
-S3_REGION
+# S3_BUCKET
 # S3_PREFIX
@@ -1,15 +1,20 @@
 FROM heroku/heroku:16-build
 WORKDIR /app
 ENV WORKSPACE_DIR="/app/builds" \
-    S3_BUCKET="lang-python" \
+    S3_BUCKET="heroku-buildpack-python" \
    S3_PREFIX="heroku-16/" \
    DEBIAN_FRONTEND=noninteractive \
    STACK="heroku-16"
-RUN apt-get update && apt-get install -y python-pip libsqlite3-dev && rm -rf /var/lib/apt/lists/*
+RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
        libsqlite3-dev \
        python3-pip \
        python3-setuptools \
    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY requirements.txt /app/
-RUN pip install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
+RUN pip3 install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
 COPY . /app
@@ -1,15 +1,20 @@
 FROM heroku/heroku:18-build
 WORKDIR /app
 ENV WORKSPACE_DIR="/app/builds" \
-    S3_BUCKET="lang-python" \
+    S3_BUCKET="heroku-buildpack-python" \
    S3_PREFIX="heroku-18/" \
    DEBIAN_FRONTEND=noninteractive \
    STACK="heroku-18"
-RUN apt-get update && apt-get install --no-install-recommends -y python-pip-whl=9.0.1-2 python-pip=9.0.1-2 python-setuptools python-wheel libsqlite3-dev && rm -rf /var/lib/apt/lists/*
+RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
        libsqlite3-dev \
        python3-pip \
        python3-setuptools \
    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY requirements.txt /app/
-RUN pip install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
+RUN pip3 install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
 COPY . /app
@@ -0,0 +1,20 @@
 FROM heroku/heroku:20-build
 ENV WORKSPACE_DIR="/app/builds" \
    S3_BUCKET="heroku-buildpack-python" \
    S3_PREFIX="heroku-20/" \
    STACK="heroku-20"
 RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
        libsqlite3-dev \
        python3-pip \
        python3-setuptools \
    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY requirements.txt /app/
 RUN pip3 install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
 COPY . /app
@@ -19,4 +19,4 @@ make install
 # Cleanup
 cd ..
-rm -fr sqlite
+rm -rf sqlite
@@ -1,24 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building gdal…"
 VERSION="2.2.1"
 SOURCE_TARBALL="http://download.osgeo.org/gdal/${VERSION}/gdal-${VERSION}.tar.gz"
 curl -L $SOURCE_TARBALL | tar zx
 pushd "gdal-${VERSION}"
 ./configure --prefix=$OUT_PREFIX --enable-static=no  &&
 make
 make install
 # Cleanup
 popd
@@ -1,25 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building geos…"
 VERSION=3.6.2
 SOURCE_TARBALL="http://download.osgeo.org/geos/geos-${VERSION}.tar.bz2"
 curl -L $SOURCE_TARBALL | tar xj
 pushd "geos-${VERSION}"
 ./configure --prefix=$OUT_PREFIX --enable-static=no &&
 make
 make install
 # Cleanup
 popd
@@ -1,45 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 if [[ $S3_PREFIX != "cedar-14" ]]; then
    echo "libmemcached only needs to be built for cedar-14, since newer stacks include it in the base image"
    exit 1
 fi
 # fail hard
 set -o pipefail
 # fail harder
 set -eux
 DEFAULT_VERSION="1.0.18"
 dep_version=${VERSION:-$DEFAULT_VERSION}
 dep_dirname=libmemcached-${dep_version}
 dep_archive_name=${dep_dirname}.tar.gz
 dep_url=https://launchpad.net/libmemcached/1.0/${dep_version}/+download/${dep_archive_name}
 # SASL Support.
 echo "-----> Building cyrus-sasl 2.1.26…"
 curl -LO ftp://ftp.cyrusimap.org/cyrus-sasl/cyrus-sasl-2.1.26.tar.gz
 # FTP doesn't play well with piping into tar xz
 tar xzf cyrus-sasl-2.1.26.tar.gz
 pushd cyrus-sasl-2.1.26
 ./configure --prefix=${OUT_PREFIX} --with-plugindir=${OUT_PREFIX}lib/sasl2 --with-configdir=${OUT_PREFIX}lib/sasl2
 make -s -j 9
 make install -s
 popd
 echo "-----> Building libmemcached ${dep_version}…"
 curl -L ${dep_url} | tar xz
 pushd ${dep_dirname}
 CPPFLAGS=-I${OUT_PREFIX}/include LDFLAGS=-L${OUT_PREFIX}/lib ./configure --prefix=${OUT_PREFIX} --without-memcached
 make -s -j 9
 make install -s
 popd
 echo "-----> Done."
@@ -1,24 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building gdal…"
 VERSION=4.9.3
 SOURCE_TARBALL="http://download.osgeo.org/proj/proj-${VERSION}.tar.gz"
 curl -L $SOURCE_TARBALL | tar zx
 pushd "proj-${VERSION}"
 ./configure --prefix=$OUT_PREFIX --enable-static=no
 make
 make install
 # Cleanup
 popd
@@ -13,11 +13,11 @@ dep_version=${dep_formula##*"/${dep_name}-"} # "subtract" our name from full ver
 dep_package=${dep_name}-v${dep_version} # it's always "pypy2-…"
 dep_dirname=${dep_package}-linux64
 dep_archive_name=${dep_dirname}.tar.bz2
-dep_url=https://bitbucket.org/pypy/pypy/downloads/${dep_archive_name}
+dep_url="https://downloads.python.org/pypy/${dep_archive_name}"
 echo "Building PyPy…"
 echo "${dep_url}"
-curl -L "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
+curl -fL "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
 ln "$OUT_PREFIX/bin/pypy" "$OUT_PREFIX/bin/python"
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/pypy2.7
@@ -13,11 +13,11 @@ dep_version=${dep_formula##*"/${dep_name}-"} # "subtract" our name from full ver
 dep_package=${dep_name}${dep_version_prefix:-}-v${dep_version}${dep_version_suffix:-}
 dep_dirname=${dep_package}-linux64
 dep_archive_name=${dep_dirname}.tar.bz2
-dep_url=https://bitbucket.org/pypy/pypy/downloads/${dep_archive_name}
+dep_url="https://downloads.python.org/pypy/${dep_archive_name}"
 echo "Building PyPy3…"
 echo "${dep_url}"
-curl -L "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
+curl -fL "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
 ln "$OUT_PREFIX/bin/pypy3" "$OUT_PREFIX/bin/python"
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/pypy3.6
@@ -1,27 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python2
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/2.7.17/Python-2.7.17.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-2.7.17 src
 cd src
 ./configure --prefix=$OUT_PREFIX  --enable-unicode=ucs4 --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
@@ -1,27 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python2
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/2.7.18/Python-2.7.18.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-2.7.18 src
 cd src
 ./configure --prefix=$OUT_PREFIX  --enable-unicode=ucs4 --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
@@ -1,32 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python3
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/3.7.2/Python-3.7.2.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-3.7.2 src
 cd src
 ./configure --prefix=$OUT_PREFIX --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
 # Remove spare /
 LOCATION=${OUT_PREFIX%?}
 ln $LOCATION/bin/python3 $LOCATION/bin/python
@@ -1,32 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python3
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/3.4.9/Python-3.4.9.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-3.4.9 src
 cd src
 ./configure --prefix=$OUT_PREFIX --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
 # Remove spare /
 LOCATION=${OUT_PREFIX%?}
 ln $LOCATION/bin/python3 $LOCATION/bin/python
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -1,5 +0,0 @@
 #!/usr/bin/env bash
 sudo apt-get -qq update
 sudo apt-get install software-properties-common
 curl --fail --retry 3 --retry-delay 1 --connect-timeout 3 --max-time 30 https://cli-assets.heroku.com/install-ubuntu.sh | sh
@@ -1,5 +1,5 @@
 ---
 - - "./repos/python/python-getting-started"
-  - master
+  - main
 - - "./repos/python/python_default"
  - ca947f69027b2a30be5d26f9a42f25e54f4d7a1a
@@ -1,3 +1,6 @@
 # Dependencies for generating/publishing Python binaries.
 bob-builder==0.0.19
 # Sub-dependencies of bob-builder.
 boto==2.49.0
 docopt==0.6.2
 bob-builder==0.0.17
 boto==2.48.0
@@ -0,0 +1 @@
 gdal
@@ -1 +0,0 @@
 django
@@ -1 +0,0 @@
 python-3.6.6
@@ -6,4 +6,4 @@ verify_ssl = true
 requests = "*"
 [requires]
-python_full_version = "3.6.3"
+python_full_version = "3.7.8"
@@ -1,24 +1,11 @@
 {
    "_meta": {
        "hash": {
-            "sha256": "22a052f4d1cfe6518b2f236fe45c3208c587a9ab1323bdd390632e27278b541e"
+            "sha256": "8a36860f0f9cb55716222098062cea5c5e0f8127cafb9d0c694de327bac9fbc0"
        },
        "host-environment-markers": {
            "implementation_name": "cpython",
            "implementation_version": "3.6.3",
            "os_name": "posix",
            "platform_machine": "x86_64",
            "platform_python_implementation": "CPython",
            "platform_release": "16.7.0",
            "platform_system": "Darwin",
            "platform_version": "Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64",
            "python_full_version": "3.6.3",
            "python_version": "3.6",
            "sys_platform": "darwin"
        },
        "pipfile-spec": 6,
        "requires": {
-            "python_full_version": "3.6.3"
+            "python_full_version": "3.7.8"
        },
        "sources": [
            {
@@ -1 +1 @@
-pypy2.7-7.2.0
+pypy2.7-7.3.2
@@ -0,0 +1 @@
 pypy2.7-7.3.1
@@ -1 +1 @@
-pypy3.6-7.2.0
+pypy3.6-7.3.2
@@ -0,0 +1 @@
 pypy3.6-7.3.1
@@ -1 +0,0 @@
 requests
@@ -1 +0,0 @@
 python-2.7.99
@@ -1 +0,0 @@
 requests
@@ -1 +0,0 @@
 flask
@@ -1 +0,0 @@
 python-3.4.99
@@ -1 +0,0 @@
 flask
@@ -1 +1 @@
-python-3.5.9
+python-3.5.10
@@ -1 +0,0 @@
 flask
@@ -1 +0,0 @@
 python-3.5.99
@@ -1 +0,0 @@
 flask
@@ -1 +1 @@
-python-3.6.8
+python-3.6.12
@@ -1 +0,0 @@
 flask
@@ -1 +0,0 @@
 python-3.6.99
@@ -1 +0,0 @@
 requests
@@ -1 +1 @@
-python-3.6.7
+python-3.6.11
@@ -1 +1 @@
-python-3.7.2
+python-3.7.9
@@ -1 +0,0 @@
 flask
@@ -1 +0,0 @@
 python-3.7.99
@@ -1 +0,0 @@
 requests
@@ -1 +1 @@
-python-3.7.1
+python-3.7.8
@@ -1 +1 @@
-python-3.8.2
+python-3.8.7
@@ -1 +0,0 @@
 flask
@@ -1 +0,0 @@
 requests
@@ -1 +1 @@
-python-3.8.0
+python-3.8.5
@@ -0,0 +1 @@
 python-3.9.0
@@ -0,0 +1 @@
 python-3.9.0
@@ -1 +0,0 @@
 flask
@@ -0,0 +1 @@
 hg+https://www.mercurial-scm.org/repo/python-hglib/#egg=python-hglib
@@ -17,21 +17,18 @@ testCollectstatic() {
  assertCaptured "collectstatic"
 }
-testGEOS() {
+testBuildWithGeoLibrariesWarning() {
  local env_dir="$(mktmpdir)"
  echo '1' > "${env_dir}/BUILD_WITH_GEO_LIBRARIES"
-  compile 'geos' '' "${env_dir}"
+  compile 'gdal' '' "${env_dir}"
-  assertCaptured "geos"
+  assertCaptured " !     The Python buildpack's legacy BUILD_WITH_GEO_LIBRARIES functonality"
-  assertCapturedSuccess
+  assertCapturedError
 }
-testGEOSDeprecation() {
+testGDALWarning() {
-  local env_dir="$(mktmpdir)"
+  compile 'gdal'
-  echo '1' > "${env_dir}/BUILD_WITH_GEO_LIBRARIES"
+  assertCaptured " !     Hello! Package installation failed since the GDAL library was not found."
-  compile 'geos' '' "${env_dir}"
+  assertCapturedError
  assertCaptured " !     The GDAL, GEOS and PROJ binaries and BUILD_WITH_GEO_LIBRARIES functonality are now deprecated.
 !     An alternative buildpack to enable GDAL, GEOS and PROJ use is available here - https://github.com/heroku/heroku-geo-buildpack"
  assertCapturedSuccess
 }
 testNLTK() {
@@ -43,7 +40,9 @@ testNLTK() {
  echo 'ignore::RuntimeWarning' > "${env_dir}/PYTHONWARNINGS"
  compile 'nltk' '' "${env_dir}"
  assertCaptured "[nltk_data] Downloading package city_database" "STD_ERR"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since the NLTK downloader outputs all
  # progress/status messages to stderr (W-8146040).
  assertCapturedSuccessWithStdErr
 }
 testPsycopg2() {
@@ -53,17 +52,16 @@ testPsycopg2() {
 }
 testPysqlite() {
  # pysqlite does not support Python 3 (since the sqlite3 stdlib can be used there),
  # so we have to test with Python 2, which we've not made available for Heroku-20.
  if [[ $STACK == "heroku-20" ]]; then
    return
  fi
  compile "pysqlite"
  assertCaptured "pysqlite"
  assertCapturedSuccess
 }
 testSqliteInstall() {
  compile "pythonDefault"
  assertNotCaptured "Sqlite3 failed to install."
  assertCapturedSuccess
 }
 testCffi() {
  compile "cffi"
  assertCaptured "cffi"
@@ -76,6 +74,12 @@ testPylibmc() {
  assertCapturedSuccess
 }
 testMercurial() {
  compile "requirements-mercurial"
  assertCaptured "Cloning hg"
  assertCapturedSuccess
 }
 pushd $(dirname 0) >/dev/null
 popd >/dev/null
@@ -33,7 +33,9 @@ testStackChange() {
 testSetupPy() {
  compile "setup-py"
  assertCaptured "maya"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since stderr contains:
  # "cp: cannot stat '/tmp/build_*/requirements.txt': No such file or directory" (W-7924941)
  assertCapturedSuccessWithStdErr
 }
 testStandardRequirements() {
@@ -45,29 +47,44 @@ testStandardRequirements() {
 testPipenv() {
  compile "pipenv"
  assertCaptured "Installing pip 9.0.2, setuptools 47.1.1 and wheel 0.34.2"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since stderr contains:
  # "cp: cannot stat '/tmp/build_*/requirements.txt': No such file or directory" (W-7924941)
  assertCapturedSuccessWithStdErr
 }
 testPipenvLock() {
  compile "pipenv-lock"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since stderr contains:
  # "cp: cannot stat '/tmp/build_*/requirements.txt': No such file or directory" (W-7924941)
  assertCapturedSuccessWithStdErr
 }
-testPipenvVersion() {
+testPipenvPythonVersion3_6() {
  compile "pipenv-version"
-  assertCaptured $DEFAULT_PYTHON_VERSION
+  assertCaptured "Installing ${LATEST_36}"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since stderr contains:
  # "cp: cannot stat '/tmp/build_*/requirements.txt': No such file or directory" (W-7924941)
  assertCapturedSuccessWithStdErr
 }
-testPipenvVersion2() {
+testPipenvPythonVersion2_7() {
  # Python 2.7 is EOL, so it has not been built for Heroku-20.
  if [[ $STACK == "heroku-20" ]]; then
    return
  fi
  compile "pipenv-version2"
-  assertCaptured $LATEST_27
+  assertCaptured "Installing ${LATEST_27}"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since stderr contains:
  # "cp: cannot stat '/tmp/build_*/requirements.txt': No such file or directory" (W-7924941)
  assertCapturedSuccessWithStdErr
 }
-testPipenvFullVersion() {
+
 testPipenvPythonFullVersion() {
  compile "pipenv-full-version"
-  assertCaptured "3.6.3"
+  assertCaptured "3.7.8"
-  assertCapturedSuccess
+  # Can't use `assertCapturedSuccess` since stderr contains:
  # "cp: cannot stat '/tmp/build_*/requirements.txt': No such file or directory" (W-7924941)
  assertCapturedSuccessWithStdErr
 }
 testNoRequirements() {
@@ -95,6 +112,7 @@ testHooks() {
  local expected_env_vars=(
    _
    BIN_DIR
    BPLOG_PREFIX
    BUILD_DIR
    BUILDPACK_LOG_FILE
    CACHE_DIR
@@ -116,9 +134,8 @@ testHooks() {
    SHLVL
    SOME_APP_CONFIG_VAR
    STACK
    VENDOR_URL
  )
-  if [[ "${STACK}" == "cedar-14" || "${STACK}" == "heroku-16" ]]; then
+  if [[ "${STACK}" == "heroku-16" ]]; then
    # Remove "OLDPWD" from expected_env_vars since for bash <4.4 it's not exported to subshells:
    # https://github.com/heroku/heroku-buildpack-python/pull/1011#issuecomment-665117835
    read -ra expected_env_vars <<< "${expected_env_vars[@]/OLDPWD/}"
@@ -4,90 +4,78 @@
 # shellcheck source=bin/default_pythons
 source "bin/default_pythons"
-testPythonDefault() {
+testPythonVersionUnspecified() {
-  updateVersion "pythonDefault" $DEFAULT_PYTHON_VERSION
+  compile "python_version_unspecified"
-  compile "pythonDefault"
+  assertCaptured "Installing ${DEFAULT_PYTHON_VERSION}"
  assertCaptured $DEFAULT_PYTHON_VERSION
  assertNotCaptured "security update"
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
  assertCapturedSuccess
 }
-testPython2() {
+testPython2_7() {
-    updateVersion "python2" $LATEST_27
+  # Python 2.7 is EOL, so it has not been built for Heroku-20.
-    echo $LATEST_27 > "runtime.txt"
+  if [[ $STACK == "heroku-20" ]]; then
-    compile "python2"
+    return
    assertCaptured $LATEST_27
    if [[ $(date "+%Y") > "2019" ]]; then
      assertCaptured "python-2-7-eol-faq";
    else
      assertNotCaptured "python-2-7-eol-faq";
  fi
  compile "python2"
  assertCaptured "Installing ${LATEST_27}"
  assertCaptured "python-2-7-eol-faq";
  assertNotCaptured "security update"
  assertCaptured "Installing pip 20.1.1, setuptools 44.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
  assertCapturedSuccess
 }
-testPython2_warn() {
+testPython2_7_warn() {
-    compile "python2_warn"
+  # Python 2.7 is EOL, so it has not been built for Heroku-20.
-    assertCaptured "python-2.7.15"
+  if [[ $STACK == "heroku-20" ]]; then
-    if [[ $(date "+%Y") > "2019" ]]; then
+    return
      assertCaptured "python-2-7-eol-faq";
    else
      assertNotCaptured "python-2-7-eol-faq";
  fi
  compile "python2_warn"
  assertCaptured "Installing python-2.7.15"
  assertCaptured "python-2-7-eol-faq";
  assertCaptured "Only the latest version"
-    assertCaptured "Installing SQLite3"
+  assertCaptured "${LATEST_27}"
  assertCapturedSuccess
 }
 testPython2_fail() {
    compile "python2_fail"
    assertCaptured "Aborting"
    assertCapturedError
 }
 testPython3_4() {
  # Python 3.4 is EOL, so it has not been built for Heroku-20.
  if [[ $STACK == "heroku-20" ]]; then
    return
  fi
  compile "python3_4"
-  assertCaptured $LATEST_34
+  assertCaptured "Installing ${LATEST_34}"
  assertNotCaptured "security update"
  assertCaptured "Installing pip 19.1.1, setuptools 43.0.0 and wheel 0.33.6"
-  # if cedar 14 and legacy binaries, fail. if cedar 14 and staging, succeed.
+  assertCaptured "Installing SQLite3"
-  if [[ ! -n $USE_STAGING_BINARIES ]] && [[ $STACK == "cedar-14" ]]; then
+  # Can't use `assertCapturedSuccess` since Pip outputs a Python 3.4 EOL warning to stderr,
-      assertCapturedError
+  # and the newest Pip that works on Python 3.4 doesn't support `PIP_NO_PYTHON_VERSION_WARNING`.
-# if heroku 18 and legacy binaries, succeed. if heroku 18 and staging, fail.
+  assertCapturedSuccessWithStdErr
  elif [[ -n $USE_STAGING_BINARIES ]] && [[ $STACK == "heroku-18" ]]; then
      assertCapturedError
  else
 #   all else succeed
    assertCapturedSuccess
  fi
 }
 testPython3_4_warn() {
-  compile "python3_4_warn"
+  # Python 3.4 is EOL, so it has not been built for Heroku-20.
-  assertCaptured "python-3.4.9"
+  if [[ $STACK == "heroku-20" ]]; then
-  assertCaptured "security update!"
+    return
 # if heroku 18 and legacy binaries, succeed. if heroku 18 and staging, fail.
  if [[ -n $USE_STAGING_BINARIES ]] && [[ $STACK == "heroku-18" ]]; then
      assertCapturedError
  else
 #   all else succeed
    assertCapturedSuccess
  fi
-}
+  compile "python3_4_warn"
-
+  assertCaptured "Installing python-3.4.9"
-testPython3_4_fail() {
+  assertCaptured "security update!"
-    compile "python3_4_fail"
+  assertCaptured "${LATEST_34}"
-    assertCaptured "Aborting"
+  # Can't use `assertCapturedSuccess` since Pip outputs a Python 3.4 EOL warning to stderr,
-    assertCapturedError
+  # and the newest Pip that works on Python 3.4 doesn't support `PIP_NO_PYTHON_VERSION_WARNING`.
  assertCapturedSuccessWithStdErr
 }
 testPython3_5() {
  # Python 3.5 is EOL, so it has not been built for Heroku-20.
  if [[ $STACK == "heroku-20" ]]; then
    return
  fi
  compile "python3_5"
-  assertCaptured $LATEST_35
+  assertCaptured "Installing ${LATEST_35}"
  assertNotCaptured "security update"
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
@@ -95,22 +83,20 @@ testPython3_5() {
 }
 testPython3_5_warn() {
  # Python 3.5 is EOL, so it has not been built for Heroku-20.
  if [[ $STACK == "heroku-20" ]]; then
    return
  fi
  compile "python3_5_warn"
-  assertCaptured "python-3.5.6"
+  assertCaptured "Installing python-3.5.6"
  assertCaptured "security update!"
  assertCaptured "${LATEST_35}"
  assertCapturedSuccess
 }
 testPython3_5_fail() {
    compile "python3_5_fail"
    assertCaptured "Aborting"
    assertCapturedError
 }
 testPython3_6() {
  updateVersion "python3_6" $LATEST_36
  compile "python3_6"
-  assertCaptured $LATEST_36
+  assertCaptured "Installing ${LATEST_36}"
  assertNotCaptured "security update"
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
@@ -119,104 +105,129 @@ testPython3_6() {
 testPython3_6_warn() {
  compile "python3_6_warn"
-  assertCaptured "python-3.6.7"
+  assertCaptured "Installing python-3.6.11"
  assertCaptured "security update!"
-  assertCaptured "Installing SQLite3"
+  assertCaptured "${LATEST_36}"
  assertCapturedSuccess
 }
 testPython3_6_fail() {
    compile "python3_6_fail"
    assertCaptured "Aborting"
    assertCapturedError
 }
 testPython3_7() {
  updateVersion "python3_7" $LATEST_37
  compile "python3_7"
-  if [[ $STACK = "cedar-14" ]]; then
+  assertCaptured "Installing ${LATEST_37}"
    assertCapturedError
  else
  assertNotCaptured "security update"
    assertCaptured $LATEST_37
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
  assertCapturedSuccess
  fi
 }
 testPython3_7_warn() {
  compile "python3_7_warn"
-  if [[ $STACK = "cedar-14" ]]; then
+  assertCaptured "Installing python-3.7.8"
    assertCapturedError
  else
    assertCaptured "python-3.7.1"
  assertCaptured "security update!"
-    assertCaptured "Installing SQLite3"
+  assertCaptured "${LATEST_37}"
  assertCapturedSuccess
  fi
 }
 testPython3_7_fail() {
  compile "python3_7_fail"
  assertCaptured "Aborting"
  assertCapturedError
 }
 testPython3_7_warn() {
  compile "python3_8_warn"
  if [[ $STACK = "cedar-14" ]]; then
    assertCapturedError
  else
    assertCaptured "python-3.8.0"
    assertCaptured "security update!"
    assertCaptured "Installing SQLite3"
    assertCapturedSuccess
  fi
 }
 testPython3_8() {
  updateVersion "python3_8" $LATEST_38
  compile "python3_8"
-  if [[ $STACK = "cedar-14" ]]; then
+  assertCaptured "Installing ${LATEST_38}"
    assertCapturedError
  else
  assertNotCaptured "security update"
    assertCaptured $LATEST_38
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
  assertCapturedSuccess
  fi
 }
-testPython3_8_fail() {
+testPython3_8_warn() {
-  compile "python3_8_fail"
+  compile "python3_8_warn"
  assertCaptured "Installing python-3.8.5"
  assertCaptured "security update!"
  assertCaptured "${LATEST_38}"
  assertCapturedSuccess
 }
 testPython3_9() {
  compile "python3_9"
  assertCaptured "Installing ${LATEST_39}"
  assertNotCaptured "security update"
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCaptured "Installing SQLite3"
  assertCapturedSuccess
 }
 testPython3_9_warn() {
  # Can't test the version warning until there is at least one old version of Python 3.9.
  if [[ "${LATEST_39}" = "python-3.9.0" ]]; then
    return
  fi
  compile "python3_9_warn"
  assertCaptured "Installing python-3.9.0"
  assertCaptured "security update!"
  assertCaptured "${LATEST_39}"
  assertCapturedSuccess
 }
 testPythonVersionInvalid() {
  compile "python_version_invalid"
  assertCaptured "Requested runtime (python-3.8.99) is not available for this stack"
  assertCaptured "Aborting"
  assertCapturedError
 }
 testPypy3_6() {
  compile "pypy3_6"
-  if [[ $STACK = "cedar-14" ]]; then
+  assertCaptured "Installing ${LATEST_PYPY_36}"
-    assertCapturedError
+  assertNotCaptured "security update"
  else
    assertCaptured "Installing pypy"
    assertCaptured "$PYPY_36"
  assertCaptured "Installing pip 20.1.1, setuptools 47.1.1 and wheel 0.34.2"
  assertCapturedSuccess
-  fi
+}
 testPypy3_6_warn() {
  compile "pypy3_6_warn"
  assertCaptured "Installing pypy3.6-7.3.1"
  assertCaptured "security update!"
  assertCaptured "${LATEST_PYPY_36}"
  assertCapturedSuccess
 }
 testPypy2_7() {
  compile "pypy2_7"
-  if [[ $STACK = "cedar-14" ]]; then
+  assertCaptured "Installing ${LATEST_PYPY_27}"
-    assertCapturedError
+  assertNotCaptured "security update"
  else
    assertCaptured "Installing pypy"
    assertCaptured "$PYPY_27"
  assertCaptured "Installing pip 20.1.1, setuptools 44.1.1 and wheel 0.34.2"
  assertCapturedSuccess
-  fi
+}
 testPypy2_7_warn() {
  compile "pypy2_7_warn"
  assertCaptured "Installing pypy2.7-7.3.1"
  assertCaptured "security update!"
  assertCaptured "${LATEST_PYPY_27}"
  assertCapturedSuccess
 }
 testStickyPythonVersion() {
  local cache_dir="$(mktmpdir)"
  compile "python3_6_warn" "$cache_dir"
  assertCaptured "Installing python-3.6.11"
  assertCapturedSuccess
  compile "python_version_unspecified" "$cache_dir"
  assertNotCaptured "Installing python"
  assertCaptured "security update!"
  assertCapturedSuccess
  # Whilst this file seems like an implementation detail (so something that should
  # not be tested), we must guarantee the filename remains consistent for backwards
  # compatibility across buildpack versions for already-built apps.
  assertFile "python-3.6.11" ".heroku/python-version"
 }
 testPythonVersionChange() {
  local cache_dir="$(mktmpdir)"
  compile "python3_6_warn" "$cache_dir"
  assertCaptured "Installing python-3.6.11"
  assertCapturedSuccess
  compile "python3_6" "$cache_dir"
  assertCaptured "Found python-3.6.11, removing"
  assertCapturedSuccess
 }
 pushd $(dirname 0) >/dev/null
@@ -56,11 +56,6 @@ resetCapture()
  unset rtrn # deprecated
 }
 updateVersion()
 {
  echo "$2" > "test/fixtures/${1}/runtime.txt"
 }
 assertCapturedEquals()
 {
  assertEquals "$@" "$(cat ${STD_OUT})"
@@ -85,12 +80,20 @@ assertNotCaptured()
 assertCapturedSuccess()
 {
  assertEquals "Captured exit code -" "0" "${RETURN}"
-  # assertEquals "STD_ERR -" "" "$(cat ${STD_ERR})"
+  assertEquals "STD_ERR -" "" "$(cat ${STD_ERR})"
-  if [ $RETURN -ne 0 -a -z "$(cat ${STD_ERR})" ]; then
+  if [ $RETURN -ne 0 -o -n "$(cat ${STD_ERR})" ]; then
-    # Failing exit code but stderr was empty. Display stdout to help debugging.
+    debug
-    cat $STD_OUT
+  fi
-    echo
+}
 assertCapturedSuccessWithStdErr()
 {
  assertEquals "Captured exit code -" "0" "${RETURN}"
  assertNotEquals "STD_ERR -" "" "$(cat ${STD_ERR})"
  if [ ${RETURN} -ne 0 ]; then
    debug
  fi
 }
@@ -151,9 +154,14 @@ _assertContains()
 debug()
 {
-  cat $STD_OUT
+  echo
-  echo '^^^^^^'
+  echo '### STD_OUT ###'
-  cat $STD_ERR
+  cat "${STD_OUT}"
  echo
  echo '### STD_ERR ###'
  cat "${STD_ERR}"
  echo
  echo
 }
 assertContains()
--- a/Show More
+++ b/Show More
		`@@ -0,0 +1 @@`
							`hg+https://www.mercurial-scm.org/repo/python-hglib/#egg=python-hglib`