https://bugs.freedesktop.org/show_bug.cgi?id=92039
--- Comment #5 from Emil Velikov emil.l.velikov@gmail.com --- So it does sound like you're having a BE system. Handful of fixes for those just landed in 10.6/11.0 I'm afraid.
Although I'm not sure why newer xserver will be required... guessing you're running a old (pre glamor, or out-of-tree glamor) one ? If you're worried about messing up your setup you can always grab a recent enough livecd or install Fedora rawhide/Archlinux/etc in a separate partition.