> The bug is still around now in Sid after the upgrade to kernel > 4.3.0.1-amd64
Hopping on to confirm. Catalyst 15.9 and Linux 4.3.0 caused Xorg to have a canary. Falling back to radeon worked just fine. I haven't tried the AMD installer yet, but I'm hoping it's actually fixed in the latest upstream version. fglrx-driver should probably be marked as broken until this is fixed upstream, so affected users can hold off.