This requires dbus >= 1.9.18.
Both Debian stretch and Ubuntu 16.04 LTS ship a new enough version so we
shouldn't need a versioned Depends (or versioned Breaks in case of
systemd).
Gbp-Dch: Short
Simon McVittie says that this needs to wait until Stretch+1 to avoid problems
on dist-upgrade due to policy files disappearing from /etc while the old
dbus-daemon is still running.
This reverts commit 5daf857c43.