Comment 2 for bug 1325600

Part of the problem is that there are two different places the "jenkins" account gets used: the Jenkins service running on the masters, and the Jenkins slave agent running on slaves. It seemed reasonable to let the slaves have a homedir in /home but the server tends to do a lot of things under its account on a Jenkins master which fits better in /var/lib, so we set the default to /home/jenkins in the jenkins::jenkinsuser class but then override it to /var/lib/jenkins in the jenkins::master class.

The correctness of these assumptions can certainly be debated, and regardless I think a comment in the master class manifest explaining this choice would probably be a good idea.