samba-ad-dc leaves a stale pidfile when not needed

The upstart script /etc/init.d/samba-ad-dc.conf runs samba -D even when the server role is "single server". This makes samba exit while leaving a stale /var/run/samba/samba.pid file.

I've monitoring scripts that watch for stale pid files in /var/run/*/*.pid, which triggers false alerts.

The older /etc/init.d/samba-ad-dc used to check the server role and skip starting samba when the role wasn't "active directory domain controller", thus no stale pidfiles were produced.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: samba 2:4.1.6+dfsg-1ubuntu2.14.04.12
ProcVersionSignature: Ubuntu 3.13.0-77.121-generic 3.13.11-ckt32
Uname: Linux 3.13.0-77-generic i686
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: i386
Date: Wed Feb 17 10:09:31 2016
OtherFailedConnect: Yes
SambaServerRegression: Yes
SmbConfIncluded: No
SourcePackage: samba
UpgradeStatus: Upgraded to trusty on 2016-01-24 (23 days ago)