Comment 2 for bug 1673398

I can confirm this.
I have fresh install of Ubuntu 17.04 and nVidia card with 2 monitors, one rotated. I can configure it correctly in gnome-flashback and generate correct xorg.conf in nvidia-settings, but the rotated secondary monitor is selected as primary on login screen and is not rotated.
I "fixed" the annoyance by autologin...

There is also a tip to use /etc/lightdm/lightdm-gtk-greeter.conf and put in
[greeter]
active-monitor=0 (probably 1 in my case)
but there is not such file and i am not sure where to put it.
There seems are some workarounds using xrandr and startup scripts.

It would be nice if this could work again.