MODE-2381 When shutting down, the bus should only set the shutdown flag after it puts the stop marker changeset in the queue. Otherwise a listener might preemptively null out the queue resulting in a NPE.
Merge pull request #1339 from hchiorean/MODE-2381

MODE-2381 When shutting down, the bus should only set the shutdown flag after it puts the stop marker changeset in the queue. Otherwise a listener might preemptively null out the queue resulting in a NPE.