调试celery + django堆栈

Question

我在Django模块中有一个操作后端数据库的Celery任务。任务开始如下：

for r in results:
    try:
        r.wait()
    except Exception as e:
        logger.error(traceback.format_exc(e))

当我运行代码时，这就是终端中发生的事情：

2012-03-26 18:19:49,153:ERROR:g: Traceback (most recent call last):
  File "./xyz.py", line 42, in g
    r.wait()
  File "/usr/local/lib/python2.7/dist-packages/celery-2.4.6-py2.7.egg/celery/result.py", line 99, in wait
    return self.get(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/celery-2.4.6-py2.7.egg/celery/result.py", line 95, in get
    interval=interval)
  File "/usr/local/lib/python2.7/dist-packages/celery-2.4.6-py2.7.egg/celery/backends/amqp.py", line 147, in wait_for
    raise self.exception_to_python(meta["result"])
IndexError: list index out of range

这个IndexError来自我的代码还是来自Celery的某个地方？如果它来自我的代码，我该如何追踪它？在调用wait（）之前和之后记录消息不会显示任何奇怪的内容。