https://bugs.freedesktop.org/show_bug.cgi?id=109925
--- Comment #4 from andrew.m.mcmahon@gmail.com --- The mesa packages provided by oibaf's ppa were updated to use LLVM 8 so I've made another trace: https://drive.google.com/open?id=1wPvrwTBTSYG7f3AQh-oolAYeXYn81ZnB
The issue is still reproducible. Again, replaying the trace has the same quirky behaviour as before.