git cl: restart using project~number on Gerrit.

This fixes Gerrit project detection based on remote URL,
accounting for potential 'a/' prefix in the URL path component,
which isn't part of the Gerrit project name.

R=ehmaldonado, mmoss

Bug: 876964, 876910
Change-Id: I473ae8c6c9e0f2034b350901abd67db151e0a3d3
Reviewed-on: https://chromium-review.googlesource.com/1187573
Reviewed-by: Michael Moss <mmoss@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>

git_cl.py

@@ -2412,6 +2412,14 @@ class _GerritChangelistImpl(_ChangelistCodereviewBase):
     project = urlparse.urlparse(remote_url).path.strip('/')
     if project.endswith('.git'):
       project = project[:-len('.git')]
+    # *.googlesource.com hosts ensure that Git/Gerrit projects don't start with
+    # 'a/' prefix, because 'a/' prefix is used to force authentication in
+    # gitiles/git-over-https protocol. E.g.,
+    # https://chromium.googlesource.com/a/v8/v8 refers to the same repo/project
+    # as
+    # https://chromium.googlesource.com/v8/v8
+    if project.startswith('a/'):
+      project = project[len('a/'):]
     return project
 
   def _GerritChangeIdentifier(self):
@@ -2419,10 +2427,8 @@ class _GerritChangelistImpl(_ChangelistCodereviewBase):
 
     Not to be confused by value of "Change-Id:" footer.
     """
-    # TODO(tandrii): undo this once a fix is in place for crbug/876964.
-    # return gerrit_util.ChangeIdentifier(
-    #     self._GetGerritProject(), self.GetIssue())
-    return str(self.GetIssue())
+    return gerrit_util.ChangeIdentifier(
+        self._GetGerritProject(), self.GetIssue())
 
   @classmethod
   def IssueConfigKey(cls):

tests/git_cl_test.py

@@ -1327,7 +1327,7 @@ class TestGitCl(TestCase):
     if squash:
       calls += [
           (('AddReviewers',
-            'chromium-review.googlesource.com', '123456',
+            'chromium-review.googlesource.com', 'my%2Frepo~123456',
             sorted(reviewers),
             ['joe@example.com', 'chromium-reviews+test-more-cc@chromium.org'] +
             cc, notify), ''),
@@ -1351,7 +1351,7 @@ class TestGitCl(TestCase):
           }),
         (('SetReview',
           'chromium-review.googlesource.com',
-          '123456',
+          'my%2Frepo~123456',
           'Self-approving for TBR',
           {'Code-Review': 2}, None), ''),
       ]
@@ -3450,6 +3450,17 @@ class TestGitCl(TestCase):
     self.assertEqual(cl.GetRemoteUrl(), url)
     self.assertEqual(cl.GetRemoteUrl(), url)  # Must be cached.
 
+  def test_gerrit_project_detection(self):
+    self.calls = [
+      ((['git', 'symbolic-ref', 'HEAD'],), 'master'),
+      ((['git', 'config', 'branch.master.merge'],), 'master'),
+      ((['git', 'config', 'branch.master.remote'],), 'origin'),
+      ((['git', 'config', 'remote.origin.url'],),
+       'https://chromium.googlesource.com/a/my/repo.git/'),
+    ]
+    cl = git_cl.Changelist(codereview='gerrit', issue=1)
+    self.assertEqual(cl._GetGerritProject(), 'my/repo')
+
 
 if __name__ == '__main__':
   logging.basicConfig(