Comment 2 for bug 535078

This error occurs when https://edge.launchpad.net/~ubuntu-wine/+archive/foo is redirected to https://edge.launchpad.net/~ubuntu-wine/+archive/ppa/foo. If "foo" contains an invalid character, you get this error. If "foo" contains no invalid characters but there's no PPA by that name, you get redirected and then get a 404. If "foo" is the name of a PPA, you get redirected and then get a 200.

I think the most correct thing to do would be to let the redirect go through and let the 404 happen after the redirect. But I don't see a good way of implementing callObject's functionality without parsing the Location header and possibly causing an InvalidURIError. So maybe we should just raise NotFound upon discovering that the Location header will send the browser to a bad place.