Code review comment for lp:~bac/launchpad/bug-496701-mimetypes

Ok, looking how it's a simple change and result of a QA-BAD on previous fix, I am ok-ing this. Since there are no automated tests here (why?), please do serious QA on staging as soon as this shows up (and as a reminder, staging gets code updated from db-stable every half an hour as long as there are no DB patches).