skip Media: links in addition to Special: links
That one triggered an exception stack trace when using Media:foo as
a target on Special:WhatLinksHere.
Example:
Special:WhatLinksHere/Media:file.png
That is a rare occurence that "should not happen". I am not sure it is
worth backporting to 1.18 although it impacts live site:
http://en.wikipedia.org/wiki/Special:WhatLinksHere/Media:BSicon_uBS2lf.svg