MDEV-9489:Assertion `0' failed in Protocol::end_statement() on UNION ALL

Restoring currect_select fixed.

mysql-test/r/subselect_mat.result

@@ -2518,3 +2518,18 @@ a	b	sq
 4	4	1
 4	2	1
 drop table t1, t2;
+#
+# MDEV-9489: Assertion `0' failed in Protocol::end_statement() on
+# UNION ALL
+#
+CREATE TABLE t1 (f1 INT);
+CREATE TABLE t2 (f2 INT);
+INSERT INTO t1 VALUES (1),(2);
+( SELECT 1 FROM t1 WHERE f1 NOT IN ( SELECT f2 FROM t2 ) LIMIT 0 )
+UNION ALL
+( SELECT 1 FROM t1 WHERE f1 NOT IN ( SELECT f2 FROM t2 ) )
+;
+1
+1
+1
+drop table t1, t2;

mysql-test/t/subselect_mat.test

@@ -254,3 +254,19 @@ SELECT a, b, (a, b) NOT IN (SELECT a, b FROM t2) as sq
 FROM t1;
 
 drop table t1, t2;
+
+--echo #
+--echo # MDEV-9489: Assertion `0' failed in Protocol::end_statement() on
+--echo # UNION ALL
+--echo #
+
+CREATE TABLE t1 (f1 INT);
+CREATE TABLE t2 (f2 INT);
+INSERT INTO t1 VALUES (1),(2);
+
+( SELECT 1 FROM t1 WHERE f1 NOT IN ( SELECT f2 FROM t2 ) LIMIT 0 )
+UNION ALL
+( SELECT 1 FROM t1 WHERE f1 NOT IN ( SELECT f2 FROM t2 ) )
+;
+
+drop table t1, t2;

sql/item_subselect.cc

@@ -5328,6 +5328,7 @@ int subselect_hash_sj_engine::exec()
     item_in->reset();
     item_in->make_const();
     item_in->set_first_execution();
+    thd->lex->current_select= save_select;
     DBUG_RETURN(FALSE);
   }
 
@@ -5371,6 +5372,7 @@ int subselect_hash_sj_engine::exec()
       item_in->null_value= 1;
       item_in->make_const();
       item_in->set_first_execution();
+      thd->lex->current_select= save_select;
       DBUG_RETURN(FALSE);
     }