Comment 44 for bug 1296020

I can confirm your fix is working Alberto :) Thank you very much.
Without it the game "The Book of Unwritten Tales" on Steam won't start (http://steamcommunity.com/app/215160/discussions/0/864973981017348556/).
I'm using Ubuntu 14.04 with the nvidia-331-updates and active nvdia-prime (sudo prime-select nvidia). Current DE ist Cinnamon from a third party PPA, but the original bug also affected at least the Gnome-Shell that comes with 14.04.
Current ubuntu-drivers-common (after activating and upgrading to propose) package is (taken info from apt-cache show):
Package: ubuntu-drivers-common

Priority: optional
Section: admin
Installed-Size: 261
Maintainer: Ubuntu Developers <email address hidden>
Architecture: i386
Version: 1:0.2.91.6
Replaces: jockey-common, jockey-gtk, jockey-kde, nvidia-common (<< 1:0.2.46)
Provides: jockey-common, jockey-gtk, jockey-kde, nvidia-common
Depends: python3:any (>= 3.3.2-2~), python3, debconf (>= 0.5.00) | debconf-2.0, libc6 (>= 2.4), libdrm2 (>= 2.4.3), libpciaccess0 (>= 0.10.7), pciutils, python3-apt, python3-xkit, udev (>= 204-0ubuntu4~), usbutils, alsa-utils, kmod | module-init-tools
Pre-Depends: dpkg (>= 1.15.7.2)
Suggests: python3-aptdaemon.pkcompat
Conflicts: jockey-common, jockey-gtk, jockey-kde, nvidia-common (<< 1:0.2.46)
Breaks: nvidia-prime (<< 0.6)
Filename: pool/main/u/ubuntu-drivers-common/ubuntu-drivers-common_0.2.91.6_i386.deb
Size: 41364
MD5sum: c95e08ea246f95d75966e3b248b9e601
SHA1: 44bbee03cc8defaea8bef6f69c71a3bbf2f49ecb
SHA256: ab98da2fbd3648ff6c722c700d19bf05bcb6f3b1669cd4d9c98f6131bcc5ab4b

Are these information enough to verificate your fix? Sorry but I'm new to this bug tracking stuff ;) Let me know if you need further info/I did waste your time with useless info ;)
And thanks again for you great work :)