https://bugs.freedesktop.org/show_bug.cgi?id=73191
--- Comment #6 from Rachel Greenham rachel@strangenoises.org --- One more finding for now.
Starting with current master, I did git revert 91aca8c662fa (the commit discovered by git bisect above) and rebuilt... and sure enough, there's no problem. There's definitely something in *that* commit that breaks it for me.
Sadly I see it's one of the bigger commits of recent times. :-} But something in there isn't right. :-)