I have enabled interhg on the crew and crew-stable repositories.

In the shortlog the summaries are links to the revision pages, therefore
replacing escaped text with something that contains an HTML link produces broken
HTML, see e.g. on http://hg.intevation.org/mercurial/crew/shortlog/ee702e7f181f
which contains nested <a></a> tags:
<a href="/mercurial/crew/rev/64888ff907f4">Fix <a
href="http://www.selenic.com/mercurial/bts/issue685">issue 685</a>: trackback in
grep -r after rename</a>

My interhg config entry:
[interhg]
pat1 = s/(?<=\W)(issue\s*)(\d+)/<a
href="http:\/\/www.selenic.com\/mercurial\/bts\/issue\2">\1\2<\/a>/