HEAP index is no longer used

CURRENT_TEST: heap.heap_hash

--- /mariadb/10.4/mysql-test/suite/heap/heap_hash.result	2019-03-15 18:06:34.123298015 +0200

+++ /mariadb/10.4/mysql-test/suite/heap/heap_hash.reject	2019-03-15 18:08:34.912797504 +0200

@@ -66,7 +66,7 @@

 alter table t1 engine=myisam;

 explain select * from t1 where a in (869751,736494,226312,802616);

 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

-1	SIMPLE	t1	index	uniq_id	uniq_id	8	NULL	5	Using where; Using index

+1	SIMPLE	t1	ALL	uniq_id	NULL	NULL	NULL	5	Using where

 drop table t1;

 create table t1 (x int not null, y int not null, key x  using HASH (x), unique y  using HASH (y))

 engine=heap;

mysqltest: Result length mismatch