heptapod-ci: automatically refresh existing phabricator Diff on push

If a changeset have been submitted to Phabricator and a new version is pushed to
heptapod, we should refresh the state on Phabricator. If we do not do this, they
are a risk of an older version being applied from Phabricator. In this situation
content-divergence will be (rightfully) detected by evolution.

We only refresh the Diff if the test pass, to avoid updating Phabricator with
broken content.

Differential Revision: https://phab.mercurial-scm.org/D9451

contrib/heptapod-ci.yml

@@ -1,5 +1,6 b''
 stages:
   - tests
+  - phabricator
 
 image: registry.heptapod.net/mercurial/ci-images/mercurial-core
 
@@ -47,6 +48,11 b' rust-cargo-test-py3:'
     variables:
         PYTHON: python3
 
+phabricator-refresh:
+    stage: phabricator
+    script:
+      - ./contrib/phab-refresh-stack.sh
+
 rust-cargo-test-py3-dirstate-tree:
     <<: *rust_cargo_test
     variables: