Run git fetch with --prune on failed git cl upload

git fetch --prune removes all references that no longer exist on remote
server. This allows git cl to upload changes to correct destination
branch.

R=ehmaldonado@chromium.org

Bug: 1149640
Change-Id: I66bf8d2209242b08991c2dae0d3a7fbc892cef87
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2606613Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

git_cl.py

@@ -2204,32 +2204,38 @@ class Changelist(object):
                       change_desc):
     """Upload the current branch to Gerrit, retry if new remote HEAD is
     found. options and change_desc may be mutated."""
+    remote, remote_branch = self.GetRemoteBranch()
+    branch = GetTargetRef(remote, remote_branch, options.target_branch)
+
     try:
       return self._CMDUploadChange(options, git_diff_args, custom_cl_base,
-                                   change_desc)
+                                   change_desc, branch)
     except GitPushError as e:
-      remote, remote_branch = self.GetRemoteBranch()
-      should_retry = remote_branch == DEFAULT_OLD_BRANCH and \
-          gerrit_util.GetProjectHead(
-              self._gerrit_host, self.GetGerritProject()) == 'refs/heads/main'
-      if not should_retry:
+      # Repository might be in the middle of transition to main branch as
+      # default, and uploads to old default might be blocked.
+      if remote_branch not in [DEFAULT_OLD_BRANCH, DEFAULT_NEW_BRANCH]:
+        DieWithError(str(e), change_desc)
+
+      project_head = gerrit_util.GetProjectHead(self._gerrit_host,
+                                                self.GetGerritProject())
+      if project_head == branch:
         DieWithError(str(e), change_desc)
+      branch = project_head
 
-    print("WARNING: Detected HEAD change in upstream, fetching remote state")
-    RunGit(['fetch', remote])
+    print("WARNING: Fetching remote state and retrying upload to default "
+          "branch...")
+    RunGit(['fetch', '--prune', remote])
     options.edit_description = False
     options.force = True
     try:
-      self._CMDUploadChange(options, git_diff_args, custom_cl_base, change_desc)
+      self._CMDUploadChange(options, git_diff_args, custom_cl_base,
+                            change_desc, branch)
     except GitPushError as e:
       DieWithError(str(e), change_desc)
 
   def _CMDUploadChange(self, options, git_diff_args, custom_cl_base,
-                       change_desc):
+                       change_desc, branch):
     """Upload the current branch to Gerrit."""
-    remote, remote_branch = self.GetRemoteBranch()
-    branch = GetTargetRef(remote, remote_branch, options.target_branch)
-
     if options.squash:
       self._GerritCommitMsgHookCheck(offer_removal=not options.force)
       if self.GetIssue():

tests/git_cl_test.py

@@ -238,6 +238,7 @@ class TestGitClBasic(unittest.TestCase):
 
     cl = git_cl.Changelist()
     options = optparse.Values()
+    options.target_branch = 'refs/heads/bar'
     with self.assertRaises(SystemExitMock):
       cl.CMDUploadChange(options, [], 'foo', git_cl.ChangeDescription('bar'))
 
@@ -256,10 +257,11 @@ class TestGitClBasic(unittest.TestCase):
     mock.patch('git_cl.Changelist.GetGerritProject',
                return_value='foo').start()
     mock.patch('git_cl.gerrit_util.GetProjectHead',
-               return_value='refs/heads/old_default').start()
+               return_value='refs/heads/master').start()
 
     cl = git_cl.Changelist()
     options = optparse.Values()
+    options.target_branch = 'refs/heads/master'
     with self.assertRaises(SystemExitMock):
       cl.CMDUploadChange(options, [], 'foo', git_cl.ChangeDescription('bar'))
 
@@ -283,6 +285,33 @@ class TestGitClBasic(unittest.TestCase):
 
     cl = git_cl.Changelist()
     options = optparse.Values()
+    options.target_branch = 'refs/heads/master'
+    cl.CMDUploadChange(options, [], 'foo', git_cl.ChangeDescription('bar'))
+    # ensure upload is called twice
+    self.assertEqual(len(m.mock_calls), 2)
+    # option overrides on retry
+    self.assertEqual(options.force, True)
+    self.assertEqual(options.edit_description, False)
+
+  def test_upload_to_old_default_retry_on_rollback(self):
+    """Test when default branch migration had to be rolled back to old name"""
+    m = mock.patch('git_cl.Changelist._CMDUploadChange',
+                   side_effect=[git_cl.GitPushError(), None]).start()
+    mock.patch('git_cl.Changelist.GetRemoteBranch',
+               return_value=('foo', git_cl.DEFAULT_NEW_BRANCH)).start()
+    mock.patch('git_cl.Changelist.GetGerritProject',
+               return_value='foo').start()
+    mock.patch('git_cl.gerrit_util.GetProjectHead',
+               return_value='refs/heads/master').start()
+    # GetTargetRef returns new default branch since it has stale remote
+    # information.
+    mock.patch('git_cl.GetTargetRef',
+               return_value='refs/heads/main').start()
+    mock.patch('git_cl.RunGit').start()
+
+    cl = git_cl.Changelist()
+    options = optparse.Values()
+    options.target_branch = 'refs/heads/master'
     cl.CMDUploadChange(options, [], 'foo', git_cl.ChangeDescription('bar'))
     # ensure upload is called twice
     self.assertEqual(len(m.mock_calls), 2)