Multiple-monitors and Nvidia Optimus not working after apt-get update/upgrade

Just recently (late August / early September 2014) my multiple monitor setup and Nvidia optimus is not working. I had the symptoms characterized by this bug. After setting the BIOS to graphics card: integrated and Optimus: disabled, I was able to start Ubuntu, but it would not detect my external monitor. Then I uninstalled and re-installed Nvidia Primus. Then I tried both suggestions in the bug tracker, involving:

sudo apt-get install ubuntu-drivers-common=1:0.2.91.4

and

sudo dpkg -i ubuntu-drivers-common_0.2.91.5_amd64.deb nvidia-common_0.2.91.5_amd64.deb 

(after downloading the associated .deb's), rebooted, and reset the BIOS to graphics card: Optimus and Optimus: enabled, but I cannot detect the external monitor. Am I missing something, or are there any suggestions on how to proceed?

I am running Ubuntu 14.04 on a Lenovo W520.

UPDATE

Now that a fix has been released on ubuntu-drivers-common, any suggestions on how to proceed? I am a bit skeptical because not all of the packages have been fixed, and the Trusty description under ubuntu-drivers-common says Triaged. Is it okay to remove the hold from the packages described below, and is there anything else I should do?

A little explanation about the meaning of the bug's status would also be helpful. My interpretation is that a fix has been released for ubuntu-drivers-common, and it is a workaround for the moment, because none of the other packages are fixed. Is that correct?

Solution 1:

I'm the OP of the askubuntu question linked in the bug.

It's hard to tell how I got it to work, but my recommendation would be:

sudo dpkg -i ubuntu-drivers-common_0.2.91.5_amd64.deb nvidia-common_0.2.91.5_amd64.deb
sudo apt-mark hold ubuntu-drivers-common
sudo apt-mark hold nvidia-common
sudo apt-get purge nvidia* bumblebee*
sudo apt-get install nvidia-331-updates nvidia-settings nvidia-prime

In other words, after the downgrade just reinstall the nvidia driver completely. Of course, feel free to replace nvidia-331-updates with the version of your choice. For me, this seems to have worked and my external screen is working as well.

Edit: Just now saw your comment that you resolved the issue. Please post that explanation in the bug report as well as it may provide useful information.

Edit #2: Glad to see that your solution is what I had suggested as well. I guess we can say this has proven to be a working workaround to downgrade.