Complete graphics freeze when watching videos in mpv fullscreen mode with
hardware acceleration enabled (vaapi), which results in GPU hang. Video plays
just fine in normal windowed mode.

After mpv crashes, following is printed on the terminal:
intel_do_flush_locked failed: Input/output errord: 47

I bisected mesa between 17.1.8 and 17.2.0 to find first bad commit to be
79f2a5541f92920d35d3621179f7377c97cc75e1

Relevant thread on Arch Linux forums:
https://bbs.archlinux.org/viewtopic.php?id=230688