Comment 72 for bug 1310023

strangely a custom symlink for nvidia_drv.so in /usr/lib/xorg/modules/drivers/ and changing
  sudo update-alternatives --config x86_64-linux-gnu_gl_conf
from nouveau to nvidia-331 kept on being undone in the filesystem. Quite unexpected for
those changes to undo themselves. ?!

Anyway, after removing the nvidia-prime and bbswitch packages from my system that's no
longer happening, so I guess I can blame them. :)

I still don't have multi-head working but at least the nvidia driver is found in Xorg.0.log now, so
I guess the rest is up to me, xorg.conf, and Xinerama or modern equivalent, and I can stop
spamming this ticket.

regards