[BR]: dpkg: warning: unable to delete old directory '/usr/lib/systemd/system': Directory not empty about fail2ban HOT 1 CLOSED

Then you get shown the scary message.

It is not "scary" at all, many packages do similar attempts (as a consequence of "pre-creation" rules), but would do that only if the directory contains only from package installed files (removed previously), so basically only empty directory.

Anyway:

1. The released here deb-file (and probably Ubuntu package) are built with branches from salsa.debian.org/.../fail2ban repo and must be basically discussed there.
2. I don't see a direct attempt to remove (or post-remove) of /usr/lib/systemd/system, but can imagine it'd done from deb itself because of this rule or here (a bit different) in debian-branch:
   

   fail2ban/debian/rules

   Line 46 in 07adcc1

   install -d $(DESTDIR)/lib/systemd/system

@sylvestre can you follow that? Is it safe to delete this rule (e. g. considering different $(DESTDIR) the directory can be missed)?

from fail2ban.