Bug#945877: ifupdown.prerm: script stops networking.service, results in network "break" (kills, e.g., ssh)

[Thomas Lamprecht]

Followup, just re-checked a Debian Stretch installation. There it's all OK,
the offending lines are missing from the prerm script. This then seems to
be a regression which was triggered by the newer compat level 12 and the
different behavior of dh_installsystemd under that level.