[Fedora-packaging] Systemd scriptlet comments

[Tom Lane]

BTW, I just noticed what seems to me a rather surprising property of the
currently recommended scriptlets for systemd migration: if the service
is currently running when you upgrade from sysv to systemd-based package
version, the service does get restarted, even though the boot start
configuration for it is intentionally not migrated.  Is this really
desirable?  It seems like a rather dangerous property, for a couple of
reasons:

(1) systemd may not know how to stop the old service correctly.
I observed exactly such a failure mode while testing mysqld, for instance
--- it tried to start the new mysqld while the old was still running.
This is no doubt related to this log message about the old service:
Jul 26 20:08:01 rhl systemd[1]: mysqld.service: Supervising process 1790 which is not our child. We'll most likely not notice when it exits.

(2) starting the new service might lull the sysadmin into a false
assumption that his boot-time start configuration for it is still there.

Now admittedly, it won't take being burned too many times for the
average user to get over problem (2), but problem (1) remains.

			regards, tom lane