Comment 4 for bug 1652640

IIUC this is the same cause as for https://bugs.launchpad.net/fuel/+bug/1648732. Because systemd package was recently added to trusty-updates repository, it breaks packages that erroneously detect systemd as the init system and try to run 'systemctl enable ...' in the post-inst script. One way to fix it is to install the systemd-shim package in this situation.