Bug#891836: systemd: systemctl start/stop/restart valid-template at invalid-instance doesn't cause errors

[Christoph Berg]

Re: Michael Biebl 2018-03-03 <87ba8f59-ec84-d3ed-c162-1fd84925690e at debian.org>
> Well, I don't think those two cases are the same and as such should be
> treated equally by systemd.
> I see typoing the template name more like adding a typo to
> ExecStart=/sbin/foobard /etc/typo_in_file_name
> In this case foobard would most likely fail to start and systemd would
> mark the service as failed. This is more comparable to your case,
> because the template name is passed as a config option to the service

In that case the error is in a config file, and marking the service as
faulty makes sense. In the unit at instancetypo case, there's nothing
wrong with the system.

(Maybe I'm overzealous here, but my first experience with systemd when
it became default in Debian was setting up postgresql at .service, and
the fact that @typo was sticking around permanently was really
freaking me out, so I was glad I figured a way to avoid it. Iirc
"systemctl reset-failed" was only invented later.)

Christoph