Comment 3 for bug 1742378

I forgot to mention one thing about the patch: the current behavior is that when on_ac_power returns 255 the current version of the script returns with that non zero error code and does not execute /usr/lib/apt/apt.systemd.daily. The patched version will execute /usr/lib/apt/apt.systemd.daily and terminate with whatever exit code that process generates.

On a side note, "which" can be replaced by "type" which is POSIX compatible and a shell built in.