Bug#1091519: deb-systemd-helper: Fails when non-existing unit is listed in Also= line

[MichaIng]

Ah sorry, looks like the missing "Also=" units really were an issue before.

However, now it is the present "Also=" units if an old package `postrm 
purge` calls "deb-systemd-helper purge" for any of them. One of our 
users reported this when upgrading from Debian Bookworm to Trixie, where 
a new version of "libvirt-daemon" was installed, and an old obsolete 
version of "libvirt-daemon-system" was finally purged.

While such, related to a distribution upgrade, may be a rare case, 
removing these After= loops remains reasonable. deb-systemd-helper will 
choke on such, and there is always a chance for such a call while units 
are still present for various reasons.

Shall I start a new bug report for this? I can also open a merge request 
at salsa, but would need to know which of the 3 units shall keep the 
"Also=" lines. The postinst script enables and starts all 3 of them, so 
from that, no most probable parent/child structure is visible.

Best regards,
Micha
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_0x0442B9ADE65643FE.asc
Type: application/pgp-keys
Size: 9878 bytes
Desc: OpenPGP public key
URL: <http://alioth-lists.debian.net/pipermail/pkg-systemd-maintainers/attachments/20250912/271add50/attachment-0001.asc>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <http://alioth-lists.debian.net/pipermail/pkg-systemd-maintainers/attachments/20250912/271add50/attachment-0001.sig>