docs: def tag(self):
          """ Return a (deferred) cached Koji tag name for this change. """
          name_or_id = self.task.tag
          if name_or_id is None:
              return defer.succeed(None)
          if isinstance(name_or_id, StringType):
              return defer.succeed(name_or_id)
          if isinstance(name_or_id, int):
              return self.task.connection.cache.tag_name(name_or_id)
          return defer.fail()