In federated server ,Rollback failed to revert update changes in transaction

MariaDB [m8]> select * from s1;

+------+

| a    |

+------+

|    1 |

|    2 |

|    3 |

+------+

3 rows in set (0.001 sec)

MariaDB [m8]> select * from s1;

+------+

| a    |

+------+

|   10 |

|   10 |

|   10 |

+------+

3 rows in set (0.003 sec)

create database m8;use m8;

create user u3@localhost; grant all on *.* to u3@localhost;

create table s1( a int);

create table s1(a int)  ENGINE="FEDERATED" CONNECTION='mysql://u3@127.0.0.1:3306/m8/s1';

truncate s1;

insert into s1 values (1),(2),(3);

start transaction;

UPDATE s1 JOIN s1 AS OUTR2 SET OUTR2.a = 10 where s1.a >0;

rollback;

select * from s1;