Now I've tried to figure out which dep was causing the problem. I managed to simulate installation of all depends and recommends of the certification provider except qt5-default.
Try to understand which dep of this package was failing I tried to install liggles2-mesa-dev and got the same errors asking to remove several xserver-xorg-.*lts-vivid packages.
ok, I can of course reproduced the error.
Now I've tried to figure out which dep was causing the problem. I managed to simulate installation of all depends and recommends of the certification provider except qt5-default.
Try to understand which dep of this package was failing I tried to install liggles2-mesa-dev and got the same errors asking to remove several xserver- xorg-.* lts-vivid packages.
To me it looks like the mesa packages even if greater than 10.1.3-0ubuntu0.4, behave exactly as in https:/ /bugs.launchpad .net/ubuntu/ +source/ mesa/+bug/ 1424466.