celery multi exits with an exception when workers use gevent

[amckinley]

When invoking celery multi with workers that use gevent, the process exits with an exit status of 0, but prints an exception that gets thrown from the threading module:

(specter)austin@ubuntu:~/src/specter/specter$ celery multi start 2 -P gevent -I specter.tasks -c 100 -E --loglevel=debug
celery multi v3.1.6 (Cipater)
> Starting nodes...
        > celery1@ubuntu: OK
        > celery2@ubuntu: OK
Exception KeyError: KeyError(14025744,) in <module 'threading' from '/usr/lib/python2.7/threading.pyc'> ignored
(specter)austin@ubuntu:~/src/specter/specter$

After discussing on IRC, the speculation is that celery multi is detecting the -P option and invoking gevent.monkey_patch() before forking the workers, which triggers the exception. See this link for details: http://stackoverflow.com/questions/8774958/keyerror-in-module-threading-after-a-successful-py-test-run