[TRIVIAL] Fix for config options merge
[TRIVIAL] Fix for config options merge

A simple bug was introduced, only caught later in QA.

mitechie/juju-gui,jrwren/juju-gui,CanonicalJS/juju-gui,jrwren/juju-gui,bac/juju-gui,CanonicalJS/juju-gui,jrwren/juju-gui,bac/juju-gui,bac/juju-gui,mitechie/juju-gui,CanonicalJS/juju-gui,mitechie/juju-gui,jrwren/juju-gui,mitechie/juju-gui,bac/juju-gui