upstart for jenkins-slave does mkdir after it has tried to use it

In /etc/init/jenkins-slave.conf, there are these lines:

pre-start script
    [ -r /etc/default/jenkins-slave ] && . /etc/default/jenkins-slave
    [ -n "$JENKINS_URL" ] || { stop; exit 0; }
    $JENKINS_ROOT/bin/download-slave.sh $JENKINS_URL
    mkdir $JENKINS_RUN > /dev/null 2>&1 || true
    chown -R $JENKINS_USER $JENKINS_RUN || true
end script

The download-slave.sh script tries to create $JENKINS_RUN/slave.jar, but $JENKINS_RUN doesn't exist yet so the slave will not start. If we change the pre-start to:

pre-start script
    [ -r /etc/default/jenkins-slave ] && . /etc/default/jenkins-slave
    [ -n "$JENKINS_URL" ] || { stop; exit 0; }
    mkdir $JENKINS_RUN > /dev/null 2>&1 || true
    chown -R $JENKINS_USER $JENKINS_RUN || true
    $JENKINS_ROOT/bin/download-slave.sh $JENKINS_URL
end script

...then all is well on restart.