rpl.rpl_parallel_optimistic failed in buildbot, failed to sync with master

rpl.rpl_parallel_optimistic 'innodb,stmt' w2 [ fail ]

        Test ended at 2018-02-06 20:43:04

CURRENT_TEST: rpl.rpl_parallel_optimistic

mysqltest: In included file "./include/sync_with_master_gtid.inc": 

included from /usr/share/mysql-test/suite/rpl/t/rpl_parallel_optimistic.test at line 306:

At line 48: Failed to sync with master

The result from queries just before the failure was:

< snip >

7	5

8	7

9	8

10	8

SELECT * FROM t2 ORDER BY a;

a	b

1	0

2	0

4	4

5	5

6	5

7	7

8	7

9	8

10	10

include/save_master_gtid.inc

connection server_2;

include/start_slave.inc

include/sync_with_master_gtid.inc

Timeout in master_gtid_wait('0-1-88', 120), current slave GTID position is: 0-1-87.