Comment # 3 on bug 1031134 from Jonathan Corbet

Sorry for the slow response, I've been away from the machine in question.

I was indeed running under X.  I installed wayland, and can now state
definitively that the problem does indeed reproduce in that environment.  I can
also attest that, under wayland, it blows away the entire session, leaving you
staring at the login screen trying to remember when you last saved your work. 
I do believe that I have tested the wayland option as much as I need to for
now.

The system does have xf86-video-intel installed.  Will remove and see what
happens thereafter.