Hum. In a way, it's simple. We're doing a region split, and it seems that the test doesn't think we will split.
In another, may be there is a real bug behind this. I'm not sure: but basically the regionserver will not stop until the split is finished. To finish it needs meta. And I guess meta is not there anymore as we're closing.
May be we should not stop the regionserver holding meta if a split is in progress?
Let see first if disabling the split helps.