Log Message:
Update mercurial to 0.9.1.

New features:
- You can now configure your 'hgweb' server to let remote users
  'push' changes over http.
- You can now 'import' a patch in a mail message by saving the mail
  message, and importing it.  This works for patches sent either
  inline or as attachments.
- The 'diff' command now accepts '-rA:B' syntax as a synonym for
  '-r A -r B', and adds '-b' and '-B' options.

For a complete list of major changes, see the announcement at
http://www.selenic.com/pipermail/mercurial/2006-July/009510.html