Bug#900880: Blank screen when rotating with xrandr

[Tomás Di Domenico <tdido@tdido.com.ar>]

Package: xserver-xorg-video-intel
Version: 2:2.99.917+git20171229-1+b1

After upgrading, rotation via xrandr of any screen in my laptop (main
one, or externals) results in the screen turning black. Mouse pointer
works as expected (i.e. rotation affects mouse movement correctly).

I solved it in the meantime by reverting to a snapshot
(20180601T043106Z) by adding it to my apt sources file, and by giving
xserver-* high priority in my apt prefences:

Package: xserver-*
Pin: origin "snapshot.debian.org"
Pin-Priority: 1001

Laptop is a Toshiba Portégé Z30-A1301 running sid.
Kernel 4.16.0-2-amd64 #1 SMP Debian 4.16.12-1 (2018-05-27).