project: Check references during sync

Symbolic references need to be checked each time sync is called, not
only for newly created repositories. For example, it is possible to
change a project name to the already existing name, and that will result
in a broken git setup without this patch: refs/ will still point to the
old repository, whereas all objects will point to the new repository.

Bug: 40013418
Change-Id: I596d29d182986804989f0562fb45090224549b0f
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/395798
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

project.py

@@ -1277,7 +1277,20 @@ class Project:
         if is_new:
             self._InitGitDir(force_sync=force_sync, quiet=quiet)
         else:
+            try:
+                # At this point, it's possible that gitdir points to an old
+                # objdir (e.g. name changed, but objdir exists). Check
+                # references to ensure that's not the case. See
+                # https://issues.gerritcodereview.com/40013418 for more
+                # details.
+                self._CheckDirReference(self.objdir, self.gitdir)
+
                 self._UpdateHooks(quiet=quiet)
+            except GitError as e:
+                if not force_sync:
+                    raise e
+                # Let _InitGitDir fix the issue, force_sync is always True here.
+                self._InitGitDir(force_sync=True, quiet=quiet)
         self._InitRemote()
 
         if self.UseAlternates: