Fix race condition in rpl_stop_start_slave. after kill connection, wait until it is gone in processlist

mysql-test/suite/rpl/t/rpl_start_stop_slave.test

@@ -28,7 +28,8 @@ set @time_before_kill := (select CURRENT_TIMESTAMP);
 
 --replace_regex /kill [0-9]*/kill <connection_id>/
 --eval kill $connection_id
-
+let $wait_condition= SELECT COUNT(*) = 0 FROM information_schema.processlist where id=$connection_id;
+--source include/wait_condition.inc
 set @time_after_kill := (select CURRENT_TIMESTAMP);
 
 --echo [Time after the query]
@@ -38,10 +39,9 @@ if(`select TIMESTAMPDIFF(SECOND,@time_after_kill, @time_before_kill) > 60`)
 --echo # assert : The difference between the timestamps 'time_after_kill' and 'time_before_kill' should be less than 60sec.
 --die
 }
-
 --echo [Killing of the slave IO thread was successful]
---disable_warnings
+
 START SLAVE IO_THREAD;
---enable_warnings
+
 # End of test
 --source include/rpl_end.inc