Backlight adjustment spews errors on OpenRC Alpine/pmOS

[samcday]

[Feb 12 22:32:29] user phrog: (gsd-power:8129): power-plugin-WARNING **: 22:32:29.307: Error executing backlight helper: Child process exited with code 127
[Feb 12 22:32:29] authpriv pkexec[8421]: greetd: The value for the SHELL variable was not found in the /etc/shells file [USER=root] [TTY=unknown] [CWD=/var/lib/greetd] [COMMAND=/usr/libexec/gsd-backlight-helper /sys/devices/platform/soc@0/1a00000.display-subsystem/1a98000.dsi/1a98000.dsi.0/backlight/1a98000.dsi.0 55] 
[Feb 12 22:32:29] user phrog: The value for the SHELL variable was not found in the /etc/shells file
[Feb 12 22:32:29] user phrog: 
[Feb 12 22:32:29] user phrog: This incident has been reported.
[Feb 12 22:32:29] user phrog: 

Guido hinted that the gsd-backlight-helper is only spawned on non-logind systems.

I don't really want to track this here since it seems more like an issue with greetd setup in Alpine. I'll timebox this to a few minutes and either open a PR in aports that fixes this or raise an issue there.