in an index.rss buffer.

(3) If I know the explicit URL of the RSS feed, say for a livejournal
    journal, I get an even more special failure.  I create the group
    by 'G m lj.debian nnrss RET
    http://www.livejournal.com/community/debian/rss', and get a
    stringp-of-list error.  It looks like this happens inside
    nnrss-check-group; if does (setq url (nnrss-discover-feed ...)),
    but what nnrss-discover-feed actually returns is an alist with the
    description, title, and href of the feed.  This patch will set url
    correctly: