Bug#749374: gdm3: Disable gdm3 service for systemd doesn't work

[Alexander Mikhailian]

Source: gdm3
Version: 3.14.1-8
Followup-For: Bug #749374

Contrary to what Osmo Salomaa reported, running

  systemctl disable gdm3
  systemctl disable gdm

did not work for me in the current testing.

JFYI, I wanted to launch Kodi without Gnome Desktop
on my HTPC.

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (900, 'testing'), (500, 'unstable')
Architecture: amd64 (x86_64)