Returns iterator of ``GitChangeset`` objects from start to end (both
        are inclusive), in ascending date order (unless ``reverse`` is set).

        :param start: changeset ID, as str; first returned changeset
        :param end: changeset ID, as str; last returned changeset
        :param start_date: if specified, changesets with commit date less than
          ``start_date`` would be filtered out from returned set
        :param end_date: if specified, changesets with commit date greater than
          ``end_date`` would be filtered out from returned set
        :param branch_name: if specified, changesets not reachable from given
          branch would be filtered out from returned set
        :param reverse: if ``True``, returned generator would be reversed
          (meaning that returned changesets would have descending date order)

        :raise BranchDoesNotExistError: If given ``branch_name`` does not
            exist.
        :raise ChangesetDoesNotExistError: If changeset for given ``start`` or
          ``end`` could not be found.

def get_changesets(self, start=None, end=None, start_date=None,
           end_date=None, branch_name=None, reverse=False):
        """
        Returns iterator of ``GitChangeset`` objects from start to end (both
        are inclusive), in ascending date order (unless ``reverse`` is set).

        :param start: changeset ID, as str; first returned changeset
        :param end: changeset ID, as str; last returned changeset
        :param start_date: if specified, changesets with commit date less than
          ``start_date`` would be filtered out from returned set
        :param end_date: if specified, changesets with commit date greater than
          ``end_date`` would be filtered out from returned set
        :param branch_name: if specified, changesets not reachable from given
          branch would be filtered out from returned set
        :param reverse: if ``True``, returned generator would be reversed
          (meaning that returned changesets would have descending date order)

        :raise BranchDoesNotExistError: If given ``branch_name`` does not
            exist.
        :raise ChangesetDoesNotExistError: If changeset for given ``start`` or
          ``end`` could not be found.

        """
        if branch_name and branch_name not in self.branches:
            raise BranchDoesNotExistError("Branch '%s' not found" \
                                          % branch_name)
        # %H at format means (full) commit hash, initial hashes are retrieved
        # in ascending date order
        cmd_template = 'log --date-order --reverse --pretty=format:"%H"'
        cmd_params = {}
        if start_date:
            cmd_template += ' --since "$since"'
            cmd_params['since'] = start_date.strftime('%m/%d/%y %H:%M:%S')
        if end_date:
            cmd_template += ' --until "$until"'
            cmd_params['until'] = end_date.strftime('%m/%d/%y %H:%M:%S')
        if branch_name:
            cmd_template += ' $branch_name'
            cmd_params['branch_name'] = branch_name
        else:
            rev_filter = settings.GIT_REV_FILTER
            cmd_template += ' %s' % (rev_filter)

        cmd = string.Template(cmd_template).safe_substitute(**cmd_params)
        revs = self.run_git_command(cmd)[0].splitlines()
        start_pos = 0
        end_pos = len(revs)
        if start:
            _start = self._get_revision(start)
            try:
                start_pos = revs.index(_start)
            except ValueError:
                pass

        if end is not None:
            _end = self._get_revision(end)
            try:
                end_pos = revs.index(_end)
            except ValueError:
                pass

        if None not in [start, end] and start_pos > end_pos:
            raise RepositoryError('start cannot be after end')

        if end_pos is not None:
            end_pos += 1

        revs = revs[start_pos:end_pos]
        if reverse:
            revs = reversed(revs)
        return CollectionGenerator(self, revs)