Hangs on redisplay_internal

[Eric Abrahamsen]

I've been updating master every three or four days, and over the past
week (more?) feel like I've been getting a lot of inexplicable hangs.
They last as long as five or six seconds, but I can usually quit out of
them. I started running with debug on quit as a matter of course, and
just managed to kill one of them, and got:

Debugger entered--Lisp error: (quit)
  redisplay_internal\ \(C\ function\)()

That's all that was in *Backtrace*.

I'm on Arch Linux, and haven't done anything special to the build
process. I know this isn't very helpful, but maybe I can track down
something more.

Thanks,
Eric