bulk update is locking to heavily...
The bulk_update code was locking the Tasks for deadlock protection, which worked, but:
- It was doing with_for_update() and should have done with_for_update(read=True) to not block reads
- It was doing the whole bulk update in one transaction, which was leaving things locked the whole time, which was sometimes locking things for long periods of time. Now I'm committing and re-locking the tasks (read=True) several times during the bulk_update, to give folks blocking on the records bein g updated a chance to get in.