I hit the very same bug, I believe it has something to do with an extra
trailing / here (shown in strace):
[pid 12372] stat("/usr/lib/xorg/modules/drivers/intel_drv.so/", 0x7ffe8ae03470) = -1 ENOTDIR (Not a directory)
[pid 12372] stat("/usr/lib/xorg/modules/drivers/modesetting_drv.so/", 0x7ffe8ae03470) = -1 ENOTDIR (Not a directory)
pid 12372 is /usr/lib/xorg/Xorg
--
\o/ Arthur
G Gandi.net