302     def _branchtip(self, heads):

   302     def _branchtip(self, heads):

   303         '''Return tuple with last open head in heads and false,

   303         '''Return tuple with last open head in heads and false,

   304         otherwise return last closed head and true.'''

   304         otherwise return last closed head and true.'''

   305         tip = heads[-1]

   305         tip = heads[-1]

   306         closed = True

   306         closed = True

   308         for h in reversed(heads):

   307         for h in reversed(heads):

   309             if h not in self._closednodes:

   308             if h not in self._closednodes:

   310                 tip = h

   309                 tip = h

   311                 closed = False

   310                 closed = False

   312                 break

   311                 break