very minor changes: a STOP SLAVE in a replication test to get rid of a non critical message in slave.err,

and a comment update

mysql-test/t/rpl_server_id2.test

@@ -18,4 +18,8 @@ insert into t1 values (1);
 save_master_pos;
 sync_with_master;
 select * from t1; # check that indeed 2 were inserted
+# We stop the slave before cleaning up otherwise we'll get
+# 'drop table t1' executed twice, so an error in the slave.err
+# (not critical).
+stop slave;
 drop table t1;