Comment 0 for bug 1636397

From a private bug:
"Currently, NVIDIA and modesetting drivers are using same output names, that creates confusion for xrandr clients like gnome-setting-daemon or xrandr utility.

When modesetting outputs act as slave for other x-screen (like NVIDIA X-screen here), modesetting driver uses different scheme of output names to avoid kind of confusion we are seeing here. There is a bug in moesetting X-driver gets shipped with X-server, which disables slave output's name scheme."

From a reviewed upstream patch:

"Commit c7e8d4a6ee9542f56cd241cf7a960fb8223a6b22 had already
unifdef MODESETTING_OUTPUT_SLAVE_SUPPORT but commit
9257b1252da9092ddc676fec9aabe2b33dfad272 didn't notice that."

so we need to backport that to zesty/yakkety/xenial.