@Makel : Canola-Cleanup for a clean unninstall, make sure you don't have ANY devel / non-safe repositories enabled, reboot (just to make sure) and install beta8 clean.

This will make sure everything is clean again.

@Adaam : same for you. You probably have more than just python launcher causing conflicts, can you send again the -vvv output? any message is helpful so we can find what happens, if the problem is on canola or a conflict or someone placing packges that shouldn't...

Marcelo