Server postinstall fails on Debian Bullseye

The issue was found by @kpfleming and described on the mailing list on 2022-09-10.

During a regular update cycle my machine tried to install isc-stork-server 1.6.0.220906131440. This failed because the post-installation script encountered an error.

Setting up isc-stork-server (1.6.0.220906131440) ...
Option s is ambiguous (shell, system)
dpkg: error processing package isc-stork-server (--configure):
installed isc-stork-server package post-installation script
subprocess returned error exit status 1

After looking at /var/lib/dpkg/info/isc-stork-server.postinst, I saw that if 'busybox' is available on the system then the post-installation script attempts to use it to create the stork-server group and user. Unfortunately the syntax appears to be bad as busybox complained, but more importantly my system is Debian Bullseye and busybox isn't used for managing users and groups... I just happened to have it installed for unrelated reasons.

I think this script's logic for determining which tool to use for managing groups and users might need to be re-thought. I was able to complete the installation by de-installing busybox.