The check for DB_RECNO seems to do the opposite of what it's supposed to do:

    def append(self, value, txn=None):
        if self.get_type() != db.DB_RECNO:
            self.append = self.__append
            return self.append(value, txn=txn)
        raise db.DBError, "append() only supported when dbshelve opened
with filetype=dbshelve.db.DB_RECNO"