Relative links pointing to the same server but being external as they do not point to the wiki but to some flatfile on the same server are not recognized properly. Instead they are mapped to be an internal link.
I'd assume that:
Which the browser will automatically map into:
Instead I get:
(with wikiserver being my machine and mkdp being my wiki location.)
I assume that the code identifies external links by matching http:// and not http: which is a pitty ;-)