Check for parent/mod as well as parent.mod in findext. Debian/Ubuntu ship a system-wide hgrc that loads extensions using the syntax hgext/extension=, rather than hgext.extension=. Although the extensions work correctly, hg help <extension> doesn't understand this form without this patch.

<div class="page_footer">
<div class="page_footer_text">#repo|escape#</div>
<a class="rss_logo" href="?cmd=changelog;style=rss">RSS</a>
</div>
</body>
</html>