rpl.semisync_future-7591 fails sporadically in buildbot

rpl.semisync_future-7591 'mix'           w1 [ fail ]

        Test ended at 2015-04-04 22:26:09

CURRENT_TEST: rpl.semisync_future-7591

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

included from ./include/check_slave_no_error.inc at line 28:

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

included from /opt/buildbot-slave/mariadb/dan_demeter2/build/mysql-test/suite/rpl/t/semisync_future-7591.test at line 32:

At line 31: Wrong value for slave parameter

The result from queries just before the failure was:

< snip >

**** SHOW BINARY LOGS on server_1 ****

SHOW BINARY LOGS;

Log_name	File_size

master-bin.000001	455

**** SHOW BINLOG EVENTS on server_1 ****

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	248	Server ver: 10.1.4-MariaDB-wsrep-log, Binlog ver: 4

master-bin.000001	248	Gtid_list	1	273	[]

master-bin.000001	273	Binlog_checkpoint	1	313	master-bin.000001

master-bin.000001	313	Gtid	1	351	GTID 0-1-1

master-bin.000001	351	Query	1	455	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';

Log_name	Pos	Event_type	Server_id	End_log_pos	Info

Wrong value for Last_IO_Errno. Expected '0', got '1593'