Desktop scale factor resets when monitor is disconnected

My system's only attached monitor, an LG 24UD58-B, disconnects itself from ports both when DPMS suspending the display, and when switching its input to another source. This disconnect/reconnect cycle causes Unity to reset the scale factor of the display from my requested 2.0 to the default of 1.0.

Gnome desktop, as supplied by Arch repositories, remembers display scaling, using its monitors.xml file, which remembers things like resolution settings, positions, and scale factors.

I am experiencing this issue with the official Unity developers' supplied Arch packages of Unity 7.6. I can try to reproduce it with the Ubuntu Unity live media, if necessary for the bug report.