In Winstone 0.9.x we used to explode war under $JENKINS_HOME/war. When we moved to Jetty-based Winstone 2.0, this code was gone and now Jetty explodes war in /tmp/jetty-0.0.0.0-8080-jenkins.war-
This tends to be problematic because various distros periodically clean up files under /tmp based on their modification dates. When exploded war files disappear from under us, all sorts of strange errors happen.
We should resurrect the old behaviour and explode the war file under $JENKINS_HOME.