when compiling RXML templates for ActionMailer views, Rails silently fails without a stack trace. It turns out that ActionView::Base.create_template_source is trying to set the content_type on a GGIReponse object via a response method in the controller. Since this is an ActionMailer object, there is no CGIResponse.
I've included a patch that fixes this issue by checking to see if the controller responds to the response method. If not, the content_type is set in the controller itself (which will really be an am object in this case).
There is also a quick test to see if the rxml template is being rendered correctly. Note that is this test is run without patching ActionView::Base.create_template_source, it will fail silently.
