st_path = os.path.join(self.path, '.hg', "store")

            if os.path.exists(cl_path):

                return os.stat(cl_path).st_mtime

            else:

                return os.stat(st_path).st_mtime

    def _get_revision(self, revision):

        """

        Gets an ID revision given as str. This will always return a fill

        40 char revision number

        :param revision: str or int or None

        """

        if isinstance(revision, unicode):

            revision = safe_str(revision)

        if self._empty:

            raise EmptyRepositoryError("There are no changesets yet")

        if revision in [-1, 'tip', None]:

            revision = 'tip'

        try:

            revision = hex(self._repo.lookup(revision))

        except (LookupError, ):

            msg = ("Ambiguous identifier `%s` for %s" % (revision, self))

            raise ChangesetDoesNotExistError(msg)

        return revision

    def get_ref_revision(self, ref_type, ref_name):

        """

        Returns revision number for the given reference.

        """

        ref_name = safe_str(ref_name)

        if ref_type == 'rev' and not ref_name.strip('0'):

            return self.EMPTY_CHANGESET

        # lookup up the exact node id

        _revset_predicates = {

                'branch': 'branch',

                'book': 'bookmark',

                'tag': 'tag',

                'rev': 'id',

            }

        # avoid expensive branch(x) iteration over whole repo

        rev_spec = "%%s & %s(%%s)" % _revset_predicates[ref_type]

        try:

            revs = self._repo.revs(rev_spec, ref_name, ref_name)

        except LookupError:

            msg = ("Ambiguous identifier %s:%s for %s" % (ref_type, ref_name, self.name))

            raise ChangesetDoesNotExistError(msg)