As a repo owner I was creating wiki page
In the screenshot there is some unclosed tag generated by your wiki before title written by me. The problematic html and wiki page part are highlighted in screenshot.
There should only be plain text title. There shouldn't be
20121017"> text before the title.
There is an unclosed
<a> tag at the beginning of the wiki page messing up the wiki page text.
I think the part of filename that goes into
<h1 id='...'> (namely the date part
20121017) is considered as a reference to changeset.