hgweb: fix unbundle. After the WSGI changes, even if a push over HTTP succeeds, apache complains about "Premature end of script headers: hgwebdir.cgi" and returns a "HTTP Error 500: Internal Server Error", making the local hg abort. The change to either of the files touched by this patch is enough to fix this, but I think changing both is a more robust solution.

Content-type: text/xml

<rss version="2.0">
  <channel>
    <link>#url#</link>
    <language>en-us</language>