When issuing `hg pull -r REV` in a repo with no common ancestor with the
remote repo, the message 'requesting all changes' is printed, even though only
the changese that are ancestors of REV are actually requested. This can be
confusing for users (see
http://www.selenic.com/pipermail/mercurial/2010-October/035508.html).
This silences the message if (and only if) the '-r' option was passed.
Previously no '# ' lines came through the parser.
Now only the first '# ' lines are processed, from '# HG changeset patch' and to
the first line not starting with '# '.
