Comment # 8 on bug 55829 from meng

It's not libdrm regression. 
It's xf86_video_intel regression, and bisected show that xf86_video_intel
1675f441049d559d891fe378e437c12db21df9e7 is the first bad commit.

commit 1675f441049d559d891fe378e437c12db21df9e7
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Jun 6 12:55:13 2012 +0100
    uxa/dri: Transfer reference of the new_back buffer to the flip_chain