Extra check for synchronization in the multi-source replication test

mysql-test/suite/multi_source/multisource.test

@@ -26,6 +26,10 @@ set default_master_connection = 'master1';
 --connection slave
 --sync_with_master 0,'master1'
 
+# Here and further: add an extra check on SQL thread status
+# as the normal sync is not always enough
+--source wait_for_sql_thread_read_all.inc
+
 # each of the 3 commands should produce 
 # 'master1' status
 
@@ -114,6 +118,8 @@ master_user='root';
 start slave;
 --source include/wait_for_slave_to_start.inc
 
+--source wait_for_sql_thread_read_all.inc
+
 # See both connections in the same status output
 
 --replace_result $SERVER_MYPORT_1 MYPORT_1 $SERVER_MYPORT_2 MYPORT_2
@@ -177,6 +183,8 @@ create table db1.t3 (f1 int) engine=InnoDB;
 --connection slave
 --sync_with_master 0,'master1'
 
+--source wait_for_sql_thread_read_all.inc
+
 --replace_result $SERVER_MYPORT_1 MYPORT_1 $SERVER_MYPORT_2 MYPORT_2
 show all slaves status;
 

mysql-test/suite/multi_source/wait_for_sql_thread_read_all.inc

+--let $show_statement = show all slaves status
+--let $field = Slave_SQL_State
+--let $condition = = 'Slave has read all relay log; waiting for the slave I/O thread to update it'
+--let $wait_for_all = 1
+--source include/wait_show_condition.inc
+