Code review comment for lp:~jimbaker/pyjuju/purge-queued-hooks

This isn't purging the right thing, and its also become clear that purging is not the correct strategy, and that the underlying cause/problem isn't addressed by it. The relation scheduler feeds into executor. Hook errors move the relation workflow, lifecycle, and scheduler into stopped states. The problem occurs when a second execution from the relation scheduler goes into the hook executor queue, prior to its stoppping. Identifying and fixing that is thhe important thing to address. Purging the scheduler while stopping isn't clearly useful.

Ie instead of inspecting the queue, we should insure the queue consumption is curtailed on error. The tests in the branch for purging queues serve only to demonstrate that information is lost by purging, not that an error'd relation won't have a hook awaiting execution in the hook executor. We should talk about this more and try to come to a more effective plan.