[DRE-maint] Bug#855828: Can't publish repositories as dpkg-scanpackages isn't isntalled

[Sjoerd Simons]

Package: obs-server
Version: 2.7.1-10
Severity: important

Hey,

Our publisher shows:
  Feb 20 13:08:00 niobium bs_publish[14097]: publish failed for home:alee:branches:apertis:16.03:development, 16.03 :     dpkg-scanpackages failed: 256

And indeed dpkg-scanpackages isn't installed. obs-server should probably
recommend dpkg-dev.

-- System Information:
Debian Release: 9.0
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, armhf

Kernel: Linux 4.9.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)