fix handling of multiple Content-type headers This can happen if an error happens while sending application/mercurial-0.1 content. The error page will be sent resulting (for at least lighttpd) in the following headers: Content-type: application/mercurial-0.1 Content-type: text/html which result in req.proto = 'application/mercurial-0.1, text/html' fix issue344

#header#
    <title>#repo|escape#: tags </title>
    <description>#repo|escape# tag history</description>
    #entriesnotip%tagentry#
  </channel>
</rss>