[pkg-netfilter-team] Bug#926728: Removing the package breaks the alternative on usr-merge system

[Laurent Bigonville]

Package: ebtables
Version: 2.0.10.4+snapshot20181205-2
Severity: serious

Hello,

On system with usr-merge, removing ebtables breaks the alternative.

The postinst script install symlinks from /sbin to /usr/sbin, in the
prerm script these symlinks are removed. BUT ebtables also add itself as
an alternative for ebtables implementations.

That means that the symlinks installed by update-alternatives are
rm when the package is removed.

Not too sure how to fix this, maybe the prerm script should check if the
symlinks directly point to a real file and only remove them in that
case?

Kind regards,
Laurent Bigonville

-- System Information:
Debian Release: buster/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (1, 'experimental-debug'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 5.0.0-trunk-amd64 (SMP w/8 CPU cores)
Locale: LANG=fr_BE.UTF-8, LC_CTYPE=fr_BE.UTF-8 (charmap=UTF-8), LANGUAGE=fr_BE:fr (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages ebtables depends on:
ii  libc6  2.28-8

Versions of packages ebtables recommends:
ii  iptables  1.8.2-4
ii  kmod      26-1

ebtables suggests no packages.