[Pkg-systemd-maintainers] Bug#741496: Bug#741496: Switching between packages providing the same Alias is broken (see syslog.service handling)

[Michael Stapelberg]

Hi Michael,

Michael Biebl <biebl at debian.org> writes:
> I fear, switching i-s-h back to remove the symlinks on "remove" might
> break certain cases again.
Agreed.

> In this particular case, I assume i-s-h doesn't update the
> /etc/systemd/system/syslog.service symlink, because it already exists.
>
> Any clever idea how to fix this?
So, my first thought was whether we could just overwrite symlinks that
point to non-existing files, but that’d be a diversion from how
“systemctl enable” behaves and foil our plan of replacing
deb-systemd-helper with a very simple wrapper/symlink even at some point
in the future.

Given that this only affects packages that share a common symlink
(so far just syslog implementations, display managers, right?), I’m not
entirely sure that we need to address this in dh-systemd itself. I mean,
certainly, it’d be better if dh-systemd could just do the right thing,
but I don’t see a good solution.

Can we work around this in the maintscripts of the affected packages
instead, perhaps by simply deleting /etc/systemd/system/syslog.service
in preinst when it points to a non-existing file?

-- 
Best regards,
Michael