You'll see that it does in fact produce the map correctly, but the bbox input isnt being populated correctly. If I do a f=image this request fails, but with f=html it at least creates the image but then appears to fail when populating the bbox input.
Looks like a services directory bug wherein it does not correctly escape the form field values.
But instead of submitting the form with f=image, if you were to try the same URL from the browser's location bar while just changing the f parameter, it works as expected:
