From 5f6941f04a084f859908921afcfe4c483e174b80 Mon Sep 17 00:00:00 2001
From: Ed Morley <501702+edmorley@users.noreply.github.com>
Date: Tue, 10 Nov 2020 14:33:52 +0000
Subject: [PATCH] Remove redundant Mercurial install step (#1111)

Mercurial is installed in the stack image for all stacks, so the
pip install of packages from Mercurial VCS URLs works without the
need for the buildpack to install it itself.

See:
https://github.com/heroku/stack-images/pull/141
https://github.com/heroku/stack-images/search?q=mercurial

Closes @W-7906950@.
---
 CHANGELOG.md                                          | 1 +
 Makefile                                              | 2 +-
 bin/compile                                           | 6 ------
 bin/steps/mercurial                                   | 9 ---------
 test/fixtures/requirements-mercurial/requirements.txt | 1 +
 test/run-deps                                         | 6 ++++++
 6 files changed, 9 insertions(+), 16 deletions(-)
 delete mode 100755 bin/steps/mercurial
 create mode 100644 test/fixtures/requirements-mercurial/requirements.txt

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dde59cd..70808c7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Remove redundant Mercurial install step (#1111).
 - Remove support for the Cedar-14 stack (#1110).
 
 ## v184 (2020-10-21)
diff --git a/Makefile b/Makefile
index 48b3fef..84668a7 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,7 @@ STACK_IMAGE_TAG := heroku/$(subst -,:,$(STACK))-build
 
 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/python
+	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/gdal bin/steps/geo-libs bin/steps/nltk bin/steps/pip-install bin/steps/pip-uninstall bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/python
 	@shellcheck -x bin/steps/hooks/*
 
 test:
diff --git a/bin/compile b/bin/compile
index 1ba32a7..150dc83 100755
--- a/bin/compile
+++ b/bin/compile
@@ -263,12 +263,6 @@ 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"
-
 # Support for Geo libraries. This is deprecated functionality.
 # It is undocumented.
 # shellcheck source=bin/steps/geo-libs
diff --git a/bin/steps/mercurial b/bin/steps/mercurial
deleted file mode 100755
index c36cb9a..0000000
--- a/bin/steps/mercurial
+++ /dev/null
@@ -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
diff --git a/test/fixtures/requirements-mercurial/requirements.txt b/test/fixtures/requirements-mercurial/requirements.txt
new file mode 100644
index 0000000..08ee098
--- /dev/null
+++ b/test/fixtures/requirements-mercurial/requirements.txt
@@ -0,0 +1 @@
+hg+https://www.mercurial-scm.org/repo/python-hglib/#egg=python-hglib
diff --git a/test/run-deps b/test/run-deps
index beb87f6..4af435f 100755
--- a/test/run-deps
+++ b/test/run-deps
@@ -74,6 +74,12 @@ testPylibmc() {
   assertCapturedSuccess
 }
 
+testMercurial() {
+  compile "requirements-mercurial"
+  assertCaptured "Cloning hg"
+  assertCapturedSuccess
+}
+
 pushd $(dirname 0) >/dev/null
 popd >/dev/null