Tags are stored in .hgtags files in any of the branches,
  so the branch metadata includes the tags as well.
  """
  h = hashlib.sha256()
  peer = hg.peer(ui, {}, url)
  for name, revs in peer.branchmap().items():
    h.update(name)
    for r in revs:
      h.update(b' ')
      h.update(r)
    h.update(b'\n')
  if (b'bookmarks' in peer.listkeys(b'namespaces')):