[DRE-maint] Bug#852043: Init script uses non-existing obsrun user

[Sjoerd Simons]

Package: obs-worker
Version: 2.7.1-9
Severity: grave

The package creates an obsworker user on install, however the init scripts
tries to chown some files to the non-existing obs-run user causing it to fail.

-- 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 4.9.0-1-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)