722         try:

   722         try:

   723             return self.index.headrevs()

   723             return self.index.headrevs()

   724         except AttributeError:

   724         except AttributeError:

   725             return self._headrevs()

   725             return self._headrevs()

   726 

   726 

   727     def _headrevs(self):

   730     def _headrevs(self):

   728         count = len(self)

   731         count = len(self)

   729         if not count:

   732         if not count:

   730             return [nullrev]

   733             return [nullrev]

   731         # we won't iter over filtered rev so nobody is a head at start

   734         # we won't iter over filtered rev so nobody is a head at start