So I followed bug 60236. I sync mesa since the proposed mesa patch had already
been pushed. I tested with kernel 3.8.0 and the bug was still there. I then
applied the proposed kernel patch over 3.8.0 (after fixing it because it was
not properly applying), built and restarted using this newly built kernel.

Result: the bug is still there and the same. So this bug is not the same as bug
60236.

I'll try to bisect mesa in the next couple of days.

BTW, I bought Bastion on Steam and tested it. The same bug appears (or not
exactly as for the demos depending of the kernel I was using), so it is not
limited to some demo cases.