files under media/ dir return 404 on bitbucket hosting (BB-3455)

see the example repo I set up here: https://bitbucket.org/idank/idank.bitbucket.org

opening http://idank.bitbucket.org doesn't show the image, nor does going to http://idank.bitbucket.org/media/aleph.png

(changing the name of the subdir fixes it)