fixed not_null_tables() for IN() (BUG#9393)

(IN() remove NULL rows only for tables from first argument (value which we looking for in IN() list) but not for tables from IN() list)
Also it will be better change Item::not_null_tables() to prohibit this optimisation by default for new created items in 5.0 or 5.1.

mysql-test/r/select.result

@@ -2515,3 +2515,12 @@ SELECT b FROM t1 WHERE b=0x8000000000000000;
 b
 9223372036854775808
 DROP TABLE t1;
+CREATE TABLE `t1` ( `gid` int(11) default NULL, `uid` int(11) default NULL);
+CREATE TABLE `t2` ( `ident` int(11) default NULL, `level` char(16) default NULL);
+INSERT INTO `t2` VALUES (0,'READ');
+CREATE TABLE `t3` ( `id` int(11) default NULL, `name` char(16) default NULL);
+INSERT INTO `t3` VALUES (1,'fs');
+select * from t3 left join t1 on t3.id = t1.uid, t2 where t2.ident in (0, t1.gid, t3.id, 0);
+id	name	gid	uid	ident	level
+1	fs	NULL	NULL	0	READ
+drop table t1,t2,t3;

mysql-test/t/select.test

@@ -2060,3 +2060,18 @@ CREATE TABLE t1 (b BIGINT(20) UNSIGNED NOT NULL, PRIMARY KEY (b));
 INSERT INTO t1 VALUES (0x8000000000000000);
 SELECT b FROM t1 WHERE b=0x8000000000000000;
 DROP TABLE t1;
+
+#
+# IN with outer join condition (BUG#9393)
+#
+CREATE TABLE `t1` ( `gid` int(11) default NULL, `uid` int(11) default NULL);
+
+CREATE TABLE `t2` ( `ident` int(11) default NULL, `level` char(16) default NULL);
+INSERT INTO `t2` VALUES (0,'READ');
+
+CREATE TABLE `t3` ( `id` int(11) default NULL, `name` char(16) default NULL);
+INSERT INTO `t3` VALUES (1,'fs');
+
+select * from t3 left join t1 on t3.id = t1.uid, t2 where t2.ident in (0, t1.gid, t3.id, 0);
+
+drop table t1,t2,t3;

sql/item_cmpfunc.h

@@ -769,6 +769,12 @@ class Item_func_in :public Item_int_func
   bool nulls_in_row();
   bool is_bool_func() { return 1; }
   CHARSET_INFO *compare_collation() { return cmp_collation.collation; }
+  /*
+    IN() protect from NULL only first argument, if construction like
+    "expression IN ()" will be allowed, we will need to check number of
+    argument here, because "NOT(NULL IN ())" is TRUE.
+  */
+  table_map not_null_tables() const { return args[0]->not_null_tables(); }
 };
 
 /* Functions used by where clause */