'Removes a completed background update task from the queue.
Args:
update_name(str): The name of the completed task to remove
Returns:
A deferred that completes once the task is removed.'

def _end_background_update(self, update_name):

    self._background_update_queue = [name for name in self._background_update_queue if (name != update_name)]
    return self._simple_delete_one('background_updates', keyvalues={'update_name': update_name})
