Add tree reference and name. (Hardlink).

def _addLink(self, dirTree, dirID, dirSeq, dirPath, name):
        """ Add tree reference and name. (Hardlink). """
        logger.debug("Link  %d-%d-%d '%s%s'", dirTree, dirID, dirSeq, dirPath, name)
        # assert dirTree != 0, (dirTree, dirID, dirSeq, dirPath, name)
        assert (dirTree, dirID, dirSeq) not in self.links, (dirTree, dirID, dirSeq)
        self.links[(dirTree, dirID, dirSeq)] = (dirPath, name)
        assert len(self.links) == 1, self.links  # Cannot have multiple hardlinks to a directory
        logger.debug("%s", self)