https://bugs.freedesktop.org/show_bug.cgi?id=90484
--- Comment #6 from Michel Dänzer michel@daenzer.net --- (In reply to Arek Ruśniak from comment #5)
r237139 is affected too, but need more time(about 100-120 sec)to trigger, this is why i didn't see it before. Now i've tried r230876 and time to trigger ~ 11 min.
The hangs before r237140 might simply be random, and might have been there for a long time if not forever. See e.g. bug 90481.