Fix formatting of message when retrying clone

Passing the force_sync variable into the string formatting results in
the message:

  "Retrying clone after deleting None"

or

  "Retrying clone after deleting True".

Pass the name of the git directory instead.

Also, move the print inside the if-block so it's only displayed
when the retry is actually going to be attempted.

Change-Id: I76d9ecc176cecee4ad512d13e9d1f6bd36aacbbb

project.py

@@ -2182,8 +2182,8 @@ class Project(object):
         try:
           self._CheckDirReference(self.objdir, self.gitdir, share_refs=False)
         except GitError as e:
-          print("Retrying clone after deleting %s" % force_sync, file=sys.stderr)
           if force_sync:
+            print("Retrying clone after deleting %s" % self.gitdir, file=sys.stderr)
             try:
               shutil.rmtree(os.path.realpath(self.gitdir))
               if self.worktree and os.path.exists(