升级到mongodb的最新版本后，我的celery任务启动失败：
celery worker --beat --app=my.celerytask.task1:worker -G <config-files> --logfile <log-file> --pidfile <pid-file>
我收到了以下错误：
[2015 - 07 - 13 11: 16: 10, 029: ERROR / Beat] beat:
Connection error: command SON([('create', u 'messages.broadcast'), ('capped', True),
('size', 100000.0)]) failed: collection already exists.Trying again in 32.0 seconds...
[2015 - 07 - 13 11: 16: 42, 190: ERROR / MainProcess] consumer: Cannot connect to mongodb:
//x.x.x.x:27017 vo-db: command SON([('create', u'messages.broadcast'),
('capped', True), ('size', 100000.0)]) failed: collection already exists.