Given a namespace preorder hash, get the associated namespace
        reveal or ready (it may be expired).

def get_namespace_by_preorder( self, preorder_hash ):
        """
        Given a namespace preorder hash, get the associated namespace
        reveal or ready (it may be expired).
        """
        cur = self.db.cursor()
        return namedb_get_namespace_by_preorder_hash( cur, preorder_hash )