rpl.kill_race_condition failed in buildbot with Wrong value for slave parameter

rpl.kill_race_condition 'row'            w4 [ fail ]

        Test ended at 2019-04-28 08:00:14

CURRENT_TEST: rpl.kill_race_condition

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

included from ./include/check_slave_no_error.inc at line 24:

included from ./include/rpl_end.inc at line 74:

included from /mnt/buildbot/build/mariadb-10.1.39/mysql-test/suite/rpl/t/kill_race_condition.test at line 28:

At line 31: Wrong value for slave parameter $slave_param

The result from queries just before the failure was:

< snip >

binlog_name = 'master-bin.000001'

SHOW BINLOG EVENTS IN 'master-bin.000001';

Log_name	Pos	Event_type	Server_id	End_log_pos	Info

master-bin.000001	4	Format_desc	1	249	Server ver: 10.1.39-MariaDB-debug, Binlog ver: 4

master-bin.000001	249	Gtid_list	1	274	[]

master-bin.000001	274	Binlog_checkpoint	1	314	master-bin.000001

master-bin.000001	314	Gtid	1	352	GTID 0-1-1

master-bin.000001	352	Query	1	438	use `test`; create table t1 (a int)

master-bin.000001	438	Gtid	1	476	BEGIN GTID 0-1-2

master-bin.000001	476	Table_map	1	517	table_id: 41 (test.t1)

master-bin.000001	517	Write_rows_v1	1	561	table_id: 41 flags: STMT_END_F

master-bin.000001	561	Query	1	630	COMMIT

master-bin.000001	630	Gtid	1	668	GTID 0-1-3

master-bin.000001	668	Query	1	772	use `test`; DROP TABLE `t1` /* generated by server */

**** SHOW RELAYLOG EVENTS on server_1 ****

relaylog_name = 'No such row'

SHOW RELAYLOG EVENTS IN 'No such row';

ERROR HY000: This command is not supported in the prepared statement protocol yet

Wrong value for Last_SQL_Errno. Expected '0', got '1927'