Error in redis exceptions

[levic]

This showed up when testing #101

If the RedisLock fails to acquire a lock then it throws an exception with the exceptions module as the argument to the exception.

• Instance 1
• Instance 2
• (exceptions is the module import)

I'm not entirely sure whether the argument is expected to be Nothing or whether it should be LOCK_FAILED, but it seems unlikely that it was intended to be the module itself. This probably wouldn't matter too much, but it does prevent the exception being able to be pickled (which means multiprocessing can't handle a child process that throws this exception)

[wolph]

You're right... silly error that needs to be fixed. It should just be nothing or some details about how/why locking failed.