multi_source.status_vars test fails sporadically in buildbot

multi_source.status_vars                 w4 [ fail ]

        Test ended at 2013-06-08 15:11:45

CURRENT_TEST: multi_source.status_vars

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

included from /usr/share/mysql/mysql-test/suite/multi_source/status_vars.test at line 92:

At line 88: 

The result from queries just before the failure was:

< snip >

set default_master_connection = 'master1';

show status like 'Slave_received_heartbeats';

Variable_name	Value

Slave_received_heartbeats	0

stop slave;

include/wait_for_slave_to_stop.inc

change master to master_heartbeat_period=2;

start slave;

include/wait_for_slave_to_start.inc

**** ERROR: failed while waiting for '' 'Slave_received_heartbeats' = '1' ****

Note: the following output may have changed since the failure was detected

**** Showing STATUS, PROCESSLIST ****

SHOW  STATUS LIKE 'Slave_received_heartbeats';

Variable_name	Value

Slave_received_heartbeats	3

SHOW PROCESSLIST;

Id	User	Host	db	Command	Time	State	Info	Progress

39	root	localhost:41582	test	Query	0	NULL	SHOW PROCESSLIST	0.000

46	system user		NULL	Connect	8	Waiting for master to send event	NULL	0.000

47	system user		NULL	Connect	8	Slave has read all relay log; waiting for the slave I/O thread to update it	NULL	0.000

More results from queries before failure can be found in /run/shm/var/4/log/status_vars.log

 - saving '/run/shm/var/4/log/multi_source.status_vars/' to '/run/shm/var/log/multi_source.status_vars/'