bug fixes and tests ...

mysql-test/r/update.result:
  Test for update with subselect and derived table ...
mysql-test/t/update.test:
  Test for update with subselect and derived table ...
sql/sql_union.cc:
  Fix for usage of ORDER BY ... and / or LIMIT .... without braces

mysql-test/r/update.result

@@ -106,9 +106,12 @@ create table t1 (a int not null, b int not null);
 insert into t1 values (1,1),(1,2),(1,3);
 update t1 set b=4 where a=1 order by b asc limit 1;
 update t1 set b=4 where a=1 order by b desc limit 1;
+create table t2 (a int not null, b int not null);
+insert into t2 values (1,1),(1,2),(1,3);
 select * from t1;
 a	b
 1	4
 1	2
 1	4
-drop table t1;
+update t1 set b=(select distinct 1 from (select * from t2) a);
+drop table t1,t2;

mysql-test/t/update.test

@@ -85,5 +85,8 @@ create table t1 (a int not null, b int not null);
 insert into t1 values (1,1),(1,2),(1,3);
 update t1 set b=4 where a=1 order by b asc limit 1;
 update t1 set b=4 where a=1 order by b desc limit 1;
+create table t2 (a int not null, b int not null);
+insert into t2 values (1,1),(1,2),(1,3);
 select * from t1;
-drop table t1;
+update t1 set b=(select distinct 1 from (select * from t2) a);
+drop table t1,t2;

sql/sql_union.cc

@@ -279,9 +279,10 @@ int st_select_lex_unit::exec()
     }
     if (!thd->fatal_error)			// Check if EOM
     {
-      offset_limit_cnt= global_parameters->offset_limit;
-      select_limit_cnt= global_parameters->select_limit+
-	global_parameters->offset_limit;
+      SELECT_LEX *sl=thd->lex.current_select->master_unit()->first_select();
+      offset_limit_cnt= (sl->braces) ? global_parameters->offset_limit : 0;
+      select_limit_cnt= (sl->braces) ? global_parameters->select_limit+
+	global_parameters->offset_limit : HA_POS_ERROR;
       if (select_limit_cnt < global_parameters->select_limit)
 	select_limit_cnt= HA_POS_ERROR;		// no limit
       if (select_limit_cnt == HA_POS_ERROR)