Bug#736258: acpid won't stop, won't upgrade (systemd) - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=736258

[Jonathan de Boyne Pollard]

ZH> $ sudo systemctl stop acpid
ZH> Job for acpid.service canceled.

... because, as noted, it's a socket-activated service, which actually
makes it two separately startable and stoppable things
("acpid.service" and "acpid.socket") in the world of systemd, only one
of which is being stopped when you're trying to take the entire
service down, with the other immediately trying to bring it back up.

And bugs #734766 and #734848 tell one the answer, which is that in
order to preserve its existing conceptual model that there is just the
one thing (named simply "acpid") invoke-rc.d should pull out the
"socket" from the "service" by looking for a "TriggeredBy="
relationship in the output of "systemctl show", and operate upon both
things together, whenever it finds a socket-activated service.
There's even an attempt at a patch that does that.