backout: backout 5d83a40cd3f8 and re-instate Python 2 support

...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 2.

Differential Revision: https://phab.mercurial-scm.org/D11757

contrib/heptapod-ci.yml

@@ -5,7 +5,7 b' stages:'
 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"
@@ -30,17 +30,30 b' variables:'
         - 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:
@@ -54,40 +67,71 b' phabricator-refresh:'
             ./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
@@ -98,6 +142,7 b' check-pytype:'
     variables:
         RUNTEST_ARGS: " --allow-slow-tests tests/test-check-pytype.t"
         HGTEST_SLOWTIMEOUT: "3600"
+        PYTHON: python3
         TEST_HGMODULEPOLICY: "c"
 
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