Bug#28497 wait_for_slave_to_stop can cause random replication mysql-test failures

 - touch up


mysql-test/include/wait_for_slave_io_to_stop.inc:
  Update comment
  Remove superfluous variable assignments

mysql-test/include/wait_for_slave_io_to_stop.inc

@@ -6,12 +6,10 @@
 #Details:
 #      1) Fill in and setup variables
 #      2) loop through looking for
-#         sql threads to stop
+#         IO thread to stop
 #      3) If loops too long die.
 ####################################################
 connection slave;
-let $my_show= SHOW SLAVE STATUS;
-let $sql_running= Slave_IO_Running;
 let $row_number= 1;
 let $run= 1;
 let $counter= 300;