
I never remember in the moment how to resolve the occasional "Missing tree" error. Every time, I have to search and eventually rediscover https://storyboard.openstack.org/#!/story/1332549 and --no-thin. Now, on error check for the "Missing tree" message and suggest --no-thin if it wasn't already enabled. Change-Id: I7be68812b68f661219a6687fea54c48bc41adac8