jenkinsci/jenkins — pull request #1087 by psr (2014-01-10 10:31:25+00:00)
Title: Use -Djava.awt.headless=true on Debian service

I installed the Jenkins Debian package, and later installed an XServer (XVFB). The graphs of test results etc. were replaced by an image suggesting that I add this flag to the JVM commandline. I don't see any reason why this shouldn't always be present on Debian systems.