How do I do в batch downgrade of packages from one repo back to canonical?

Ubuntu 15.10 x86_64 While trying to do an install of Bumblebee, I followed instructions to add the xorg-edgers PPA. В more recent руководитель advised against it. However, by then, it was already too лает: several packages were already updated to the xorg-edgers versions.

I thought I might be able to go into Synaptic and вынудил версию these packages back to Canonical. This worked for some packages, but it quickly turned into в dependency nightmare. Some downgrades wanted to uninstall other packages, and some (libegl1-mesa-dev), if elected to be downgraded rather than переместите, threatened to uninstall nearly every package currently installed, including everything xorg.

Is there an easy way to roll back everything from в PPA back to Canonical?

** In response to "possible удвойся", removing the PPA wasn't the problem, but rather rolling back the packages without causing в firestorm of dependency problems proved most challenging. However, in the suggested answer, the solution to my question was also given; namely, the ppa-purge solution.