index_merge.result:

  Fixed inconsistency of values of used_tables_cache
  and const_item_cache for Item_func_isnull objects (bug #1990).

mysql-test/r/index_merge.result

@@ -76,13 +76,13 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t0	ALL	i1,i2	NULL	NULL	NULL	1024	Using where
 explain select * from t0 where key2 = 45 or key1 is null;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t0	ALL	i1,i2	NULL	NULL	NULL	1024	Using where
+1	SIMPLE	t0	range	i1,i2	i2	4	NULL	1	Using where
 explain select * from t0 where key2=10 or key3=3 or key4 <=> null;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t0	index_merge	i2,i3,i4	i2,i3	4,4	NULL	2	Using where
 explain select * from t0 where key2=10 or key3=3 or key4 is null;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t0	ALL	i2,i3,i4	NULL	NULL	NULL	1024	Using where
+1	SIMPLE	t0	index_merge	i2,i3,i4	i2,i3	4,4	NULL	2	Using where
 explain select key1 from t0 where (key1 <=> null) or (key2 < 5) or 
 (key3=10) or (key4 <=> null);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra