backout: backed out changeset 5d83a40cd3f8

This is the re-send of the backout in D11757 that I accidentally queued. I'll
rewrite the original commit message:

...sigh

We do not have Python 3 packaging for thg on Windows where the vast majority of
of users use the thg installer for Mercurial. Until this is done (hopefully
this cycle), we're keeping Python.

(end of the old commit message)

On top of this, we have a solid lead to have competent people take care of this
packaging issue for us in time for the 6.1 release, which is really the main
reason for us to wait. We're trying our best to make this work, so please bear
with us.

Differential Revision: https://phab.mercurial-scm.org/D11770

contrib/heptapod-ci.yml

@@ -1,142 +1,187 b''
 stages:
   - tests
   - phabricator
 
 image: registry.heptapod.net/mercurial/ci-images/mercurial-core:$HG_CI_IMAGE_TAG
 
 variables:
-    PYTHON: python3
+    PYTHON: python
     TEST_HGMODULEPOLICY: "allow"
     HG_CI_IMAGE_TAG: "latest"
     TEST_HGTESTS_ALLOW_NETIO: "0"
 
 .all_template: &all
   when: always
 
 .runtests_template: &runtests
     <<: *all
     stage: tests
     # The runner made a clone as root.
     # We make a new clone owned by user used to run the step.
     before_script:
       - hg clone . /tmp/mercurial-ci/ --noupdate --config phases.publish=no
       - hg -R /tmp/mercurial-ci/ update `hg log --rev '.' --template '{node}'`
       - cd /tmp/mercurial-ci/
       - ls -1 tests/test-check-*.* > /tmp/check-tests.txt
       - black --version
       - clang-format --version
     script:
         - echo "python used, $PYTHON"
         - echo "$RUNTEST_ARGS"
         - HGTESTS_ALLOW_NETIO="$TEST_HGTESTS_ALLOW_NETIO" HGMODULEPOLICY="$TEST_HGMODULEPOLICY" "$PYTHON" tests/run-tests.py --color=always $RUNTEST_ARGS
 
-checks:
+checks-py2:
     <<: *runtests
     variables:
         RUNTEST_ARGS: "--time --test-list /tmp/check-tests.txt"
 
-rust-cargo-test:
+checks-py3:
+    <<: *runtests
+    variables:
+        RUNTEST_ARGS: "--time --test-list /tmp/check-tests.txt"
+        PYTHON: python3
+
+rust-cargo-test-py2: &rust_cargo_test
     <<: *all
     stage: tests
     script:
+        - echo "python used, $PYTHON"
         - make rust-tests
 
+rust-cargo-test-py3:
+    stage: tests
+    <<: *rust_cargo_test
+    variables:
+        PYTHON: python3
+
 phabricator-refresh:
     stage: phabricator
     variables:
       DEFAULT_COMMENT: ":white_check_mark: refresh by Heptapod after a successful CI run (:octopus: :green_heart:)"
       STABLE_COMMENT: ":white_check_mark: refresh by Heptapod after a successful CI run (:octopus: :green_heart:)\n⚠ This patch is intended for stable ⚠\n{image https://media.giphy.com/media/nYI8SmmChYXK0/source.gif}"
     script:
       - |
         if [ `hg branch` == "stable" ]; then
             ./contrib/phab-refresh-stack.sh --comment "$STABLE_COMMENT";
         else
             ./contrib/phab-refresh-stack.sh --comment "$DEFAULT_COMMENT";
         fi
 
-test:
+test-py2:
     <<: *runtests
     variables:
         RUNTEST_ARGS: " --no-rust --blacklist /tmp/check-tests.txt"
         TEST_HGMODULEPOLICY: "c"
         TEST_HGTESTS_ALLOW_NETIO: "1"
 
-test-pure:
+test-py3:
+    <<: *runtests
+    variables:
+        RUNTEST_ARGS: " --no-rust --blacklist /tmp/check-tests.txt"
+        PYTHON: python3
+        TEST_HGMODULEPOLICY: "c"
+        TEST_HGTESTS_ALLOW_NETIO: "1"
+
+test-py2-pure:
     <<: *runtests
     variables:
         RUNTEST_ARGS: "--pure --blacklist /tmp/check-tests.txt"
         TEST_HGMODULEPOLICY: "py"
 
-test-rust:
+test-py3-pure:
+    <<: *runtests
+    variables:
+        RUNTEST_ARGS: "--pure --blacklist /tmp/check-tests.txt"
+        PYTHON: python3
+        TEST_HGMODULEPOLICY: "py"
+
+test-py2-rust:
     <<: *runtests
     variables:
         HGWITHRUSTEXT: cpython
         RUNTEST_ARGS: "--rust --blacklist /tmp/check-tests.txt"
         TEST_HGMODULEPOLICY: "rust+c"
 
-test-rhg:
+test-py3-rust:
+    <<: *runtests
+    variables:
+        HGWITHRUSTEXT: cpython
+        RUNTEST_ARGS: "--rust --blacklist /tmp/check-tests.txt"
+        PYTHON: python3
+        TEST_HGMODULEPOLICY: "rust+c"
+
+test-py3-rhg:
     <<: *runtests
     variables:
         HGWITHRUSTEXT: cpython
         RUNTEST_ARGS: "--rust --rhg --blacklist /tmp/check-tests.txt"
+        PYTHON: python3
         TEST_HGMODULEPOLICY: "rust+c"
 
-test-chg:
+test-py2-chg:
     <<: *runtests
     variables:
         RUNTEST_ARGS: "--blacklist /tmp/check-tests.txt --chg"
         TEST_HGMODULEPOLICY: "c"
 
-check-pytype:
+test-py3-chg:
+    <<: *runtests
+    variables:
+        PYTHON: python3
+        RUNTEST_ARGS: "--blacklist /tmp/check-tests.txt --chg"
+        TEST_HGMODULEPOLICY: "c"
+
+check-pytype-py3:
     extends: .runtests_template
     before_script:
       - hg clone . /tmp/mercurial-ci/ --noupdate --config phases.publish=no
       - hg -R /tmp/mercurial-ci/ update `hg log --rev '.' --template '{node}'`
       - cd /tmp/mercurial-ci/
       - make local PYTHON=$PYTHON
       - $PYTHON -m pip install --user -U pytype==2021.04.15
     variables:
         RUNTEST_ARGS: " --allow-slow-tests tests/test-check-pytype.t"
         HGTEST_SLOWTIMEOUT: "3600"
+        PYTHON: python3
         TEST_HGMODULEPOLICY: "c"
 
 # `sh.exe --login` sets a couple of extra environment variables that are defined
 # in the MinGW shell, but switches CWD to /home/$username.  The previous value
 # is stored in OLDPWD.  Of the added variables, MSYSTEM is crucial to running
 # run-tests.py- it is needed to make run-tests.py generate a `python3` script
 # that satisfies the various shebang lines and delegates to `py -3`.
 .window_runtests_template: &windows_runtests
     <<: *all
     stage: tests
     before_script:
       - C:/MinGW/msys/1.0/bin/sh.exe --login -c 'cd "$OLDPWD" && ls -1 tests/test-check-*.* > C:/Temp/check-tests.txt'
       # TODO: find/install cvs, bzr, perforce, gpg, sqlite3
 
     script:
         - echo "Entering script section"
         - echo "python used, $Env:PYTHON"
         - Invoke-Expression "$Env:PYTHON -V"
         - Invoke-Expression "$Env:PYTHON -m black --version"
         - echo "$Env:RUNTEST_ARGS"
         - echo "$Env:TMP"
         - echo "$Env:TEMP"
 
         - C:/MinGW/msys/1.0/bin/sh.exe --login -c 'cd "$OLDPWD" && HGTESTS_ALLOW_NETIO="$TEST_HGTESTS_ALLOW_NETIO" HGMODULEPOLICY="$TEST_HGMODULEPOLICY" $PYTHON tests/run-tests.py --color=always $RUNTEST_ARGS'
 
 windows-py3:
     <<: *windows_runtests
     tags:
       - windows
     variables:
         TEST_HGMODULEPOLICY: "c"
         RUNTEST_ARGS: "--blacklist C:/Temp/check-tests.txt"
         PYTHON: py -3
 
 windows-py3-pyox:
     <<: *windows_runtests
     tags:
       - windows
     variables:
         TEST_HGMODULEPOLICY: "c"
         RUNTEST_ARGS: "--blacklist C:/Temp/check-tests.txt --pyoxidized"
         PYTHON: py -3