in systemd.postinst is an Ubuntu delta from Debian, which was originally introduced in to fix bug 1748147. If a package just lets debhelper generate its systemd-tmpfiles and systemd-sysusers calls (dh_installtmpfiles and dh_installsysusers), then each package's postinst will call systemd-tmpfiles and systemd-sysusers such that *only* configurations shipped by the package are processed.
From a quick investigation, it seems that we might not need the fix for bug 1748147 any longer (calling systemd-tmpfiles --create var.conf after systemd-tmpfiles --create 00rsyslog.conf does not undo the syslog changes). Hence, dropping this call from systemd.postinst might be the right fix.
So the call of:
systemd-tmpfiles --create || :
in systemd.postinst is an Ubuntu delta from Debian, which was originally introduced in to fix bug 1748147. If a package just lets debhelper generate its systemd-tmpfiles and systemd-sysusers calls (dh_installtmpfiles and dh_installsysus ers), then each package's postinst will call systemd-tmpfiles and systemd-sysusers such that *only* configurations shipped by the package are processed.
From a quick investigation, it seems that we might not need the fix for bug 1748147 any longer (calling systemd-tmpfiles --create var.conf after systemd-tmpfiles --create 00rsyslog.conf does not undo the syslog changes). Hence, dropping this call from systemd.postinst might be the right fix.