Bug#870641: light-locker: screen stays black after closing and opening laptop lid

[Aaron Lu <aaron.lwe@gmail.com>]

Another weird thing: on 4.19.0-9, if I leave the screen/display off long
enough, like:
1 lock the screen
2 see the display off
3 go out for lunch
4 when return, typing or moving mouse can bring the display back on.

As comparison, if I leave the screen/display off not long enough, like
going to take some drink, when I get back, in 4), the display won't be
powered back on by typing or moving mouse.

I have no idea of what happened...