For our environment it is required to load webapp into /var/cache/jenkins.
With previous version (1.509.3) setting /etc/default/jenkins with:
JENKINS_ARGS="--webroot=/var/cache/jenkins/war --httpPort=$HTTP_PORT --ajp13Port=$AJP_PORT"

has always loaded webroot/webapp to this location.
Installing the latest jenkins with 'apt-get install -y jenkins' using our existing /etc/default/jenkins file not passing the --webroot parameter/location. Starting Jenkins with /etc/init.d/jenkins start

Jenkins:IIRC suggestions to use (command-line or /etc/default/jenkins):
$ export JETTY_HOME=/var/cache/jenkins/war
$ export JENKINS_HOME=/home/username/jenkins
$ /usr/bin/java -Xmx512m -jar /usr/share/jenkins/jenkins-1.540.war --webroot=/var/cache/jenkins/war --httpPort=8080 --ajp13Port=-1

However, it still continuously loads into: /tmp/jetty-0.0.0.0-8080-jenkins-1.540.war-any/webapp

/var/log/jenkins/jenkins.log:
INFO: Extract jar:file:/usr/share/jenkins/jenkins-1.540.war!/ to /tmp/jetty-0.0.0.0-8080-jenkins-1.540.war-any/webapp

Using previous 1.509.3 jenkins.war (and prior) versions does not have this behavior.

Is this change by design?
Can you please provide a workaround so we can specify --webroot or jetty_home, etc.?