Ok so this is probably due to the version of the DHs used when generating the postrm script during packaging.
On my system, the diversity is quite large regarding all the installed packages and the dh_installsystemd: $ grep -ho 'dh_installsystemd/.\+' /var/lib/dpkg/info/*.postrm | cut -d '/' -f 2 | sort -u 13.10 13.11.1 13.11.4 13.11.6 13.11.7 13.11.8 13.11.9 13.13 13.14.1 13.15.2 13.15.3 When to decided to rebuild a package (binnmu sort of) due to a possible DH trouble? For a given (old)stable release, is this more homogeneous? Under control by any QA tool? Regards, Patrice