Comment 4 for bug 538219

Yes, it's the extension that isn't liked. There are two ways to consider this bug: 1) it's an issue with zope.contenttype and Python's mimetypes module which relies on extensions rather than magic numbers or similar to determine file type, or 2) it's an issue with Launchpad relying on zope.contenttype rather than running a job that tests compatibility with patch or bzrz patch or something.