Routing callback cannot set optional parameters

[v-dogg]

routing.xml:

<route name="test" pattern="^(/{test:\d+})?/foo" module="Default" action="Foo" callback="TestCallback" />

callback's onGenerate:

if (!isset($userParameters['test'])) {
  $userParameters['test'] = 'automatic';
}
return true;

Now I would expect $this->context->getRouting()->gen('test'); to generate /automatic/foo but the optional parameter is ignored. HOWEVER if the the isset-test is removed and the optional parameter is given, the callback overwrites it.

[david]

(In [2118]) Fixed problem where routing callbacks could not set optional parameters, closes #579