Bug#902287: systemctl unmask --runtime no longer supported

[Carl Suster]

On Sun, 24 Jun 2018 16:25:14 +0200 Michael Biebl <biebl at debian.org> 
wrote> According to codesearch we currently have two packages in the archive
> using unmask --runtime: avahi and policykit-1
> 
> https://sources.debian.org/src/avahi/0.7-3.1/debian/avahi-daemon.postrm/?hl=7#L7
> 
> https://sources.debian.org/src/policykit-1/0.105-20/debian/policykit-1.postinst/?hl=58#L58
> https://sources.debian.org/src/policykit-1/0.105-20/debian/policykit-1.preinst/?hl=15#L15

The postrm script of modemmanager is also affected: see #902260.