After updating xserver-xorg-video-intel from 2.9.1-1 to 2.9.1-2 I was no longer able to use Xv (gst-launch videotestsrc ! xvimgesink did not work). Removing /etc/modprobe.d/i915-kms.conf and rebooting solved the problem. I can reload i915 with modeset=1 and restart X if a logfile exhibiting old behaviour would be useful.