Fixed locking in JobQueueAggregatorRedis

* The old code would still bump the lock TTL on failure,
  so if processes kept trying to acquire it and the one
  that had it crashed, nothing would ever do anything.

Change-Id: If3fe7b75364204f399fb4caf8bd39204ab51b353
Merge "Fixed locking in JobQueueAggregatorRedis"