fixed LIMIT clause printing (BUG#4839)

mysql-test/r/view.result

@@ -1042,3 +1042,8 @@ SHOW TABLES;
 Tables_in_test	table_type
 t2	BASE TABLE
 v4	VIEW
+CREATE VIEW v1 AS SELECT EXISTS (SELECT 1 UNION SELECT 2);
+select * from v1;
+EXISTS (SELECT 1 UNION SELECT 2)
+1
+drop view v1;

mysql-test/t/view.test

@@ -980,3 +980,10 @@ drop table t1;
 -- error 1096
 CREATE VIEW v02 AS SELECT * FROM DUAL;
 SHOW TABLES;
+
+#
+# EXISTS with UNION VIEW
+#
+CREATE VIEW v1 AS SELECT EXISTS (SELECT 1 UNION SELECT 2);
+select * from v1;
+drop view v1;

sql/sql_lex.cc

@@ -1481,8 +1481,9 @@ void st_select_lex::print_order(String *str, ORDER *order)
 
 void st_select_lex::print_limit(THD *thd, String *str)
 {
-  Item_subselect *item= master_unit()->item;
-  if (item &&
+  SELECT_LEX_UNIT *unit= master_unit();
+  Item_subselect *item= unit->item;
+  if (item && unit->global_parameters == this &&
       (item->substype() == Item_subselect::EXISTS_SUBS ||
        item->substype() == Item_subselect::IN_SUBS ||
        item->substype() == Item_subselect::ALL_SUBS))