Python 3 default for buildpack (#409)

* update default python to 3.6.1

* v110

* nltk python2

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Python Buildpack Changelog
 
+# 110
+
+Update Default Python to 3.6.1, bugfixes.
+
+- Fixed automatic pip uninstall of dependencies removed from requirements.txt.
+
 # 109
 
 Fix output for collectstatic step.

bin/compile

@@ -32,7 +32,7 @@ CACHE_DIR=$2
 ENV_DIR=$3
 
 # Python defaults
-DEFAULT_PYTHON_VERSION="python-2.7.13"
+DEFAULT_PYTHON_VERSION="python-3.6.1"
 DEFAULT_PYTHON_STACK="cedar-14"
 PYTHON_EXE="/app/.heroku/python/bin/python"
 PIP_VERSION="9.0.1"
@@ -170,16 +170,16 @@ sub-env $BIN_DIR/steps/geo-libs
 # GDAL support.
 source $BIN_DIR/steps/gdal
 
-# Install dependencies with Pip (where the magic happens).
-let start=$(nowms)
-source $BIN_DIR/steps/pip-install
-mtime "pip.install.time" "${start}"
-
 # Uninstall removed dependencies with Pip.
 let start=$(nowms)
 source $BIN_DIR/steps/pip-uninstall
 mtime "pip.uninstall.time" "${start}"
 
+# Install dependencies with Pip (where the magic happens).
+let start=$(nowms)
+source $BIN_DIR/steps/pip-install
+mtime "pip.install.time" "${start}"
+
 # Support for NLTK corpora.
 let start=$(nowms)
 sub-env $BIN_DIR/steps/nltk

builds/runtimes/pypy3-5.8.0

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# Build Path: /app/.heroku/python/
+# Build Deps: libraries/sqlite
+
+OUT_PREFIX=$1
+
+echo "Building PyPy..."
+SOURCE_TARBALL='https://bitbucket.org/pypy/pypy/downloads/pypy3-v5.8.0-linux64.tar.bz2'
+curl -L $SOURCE_TARBALL | tar jx
+cp -R pypy3-v5.8.0-linux64/* $OUT_PREFIX
+
+ln $OUT_PREFIX/bin/pypy3 $OUT_PREFIX/bin/python

test/fixtures/nltk/runtime.txt

@@ -0,0 +1 @@
+python-2.7.13

test/run

@@ -62,6 +62,16 @@ testPython3() {
   assertCapturedSuccess
 }
 
+testSmartRequirements() {
+  local cache_dir="$(mktmpdir)"
+  compile "requirements-standard" "$cache_dir"
+  assertFile "requests" ".heroku/python/requirements-declared.txt"
+  assertCapturedSuccess
+  compile "psycopg2" "$cache_dir"
+  assertCaptured "Uninstalling requests"
+  assertFile "psycopg2" ".heroku/python/requirements-declared.txt"
+  assertCapturedSuccess
+}