Minor Description
XmlAjaxResponse#writeComponent() erroneously sets the passed response into the requestCycle, although it never was the old (=original) response:
@Override
protected void writeComponent(Response response, ...)
{
...
// Restore original response
RequestCycle.get().setResponse(response);
}
AjaxRequestHandler#respond(...) restores the correct old response afterwards, but temporarily the current response of the RequestCycle is wrong.