docs: def ensure_clean(self):
          """
          Make sure the working tree is clean (contains no changes to tracked files).
  
          :raises: :exc:`~vcs_repo_mgr.exceptions.WorkingTreeNotCleanError`
                   when the working tree contains changes to tracked files.
          """
          if not self.is_clean:
              raise WorkingTreeNotCleanError(compact("""
                  The repository's local working tree ({local})
                  contains changes to tracked files!
              """, local=format_path(self.local)))