main.type_blob failed in buildbot with wrong result

main.type_blob                           w1 [ fail ]

        Test ended at 2018-01-08 04:21:58

CURRENT_TEST: main.type_blob

--- /usr/share/mysql/mysql-test/r/type_blob.result	2018-01-08 02:48:57.000000000 -0500

+++ /dev/shm/var/1/log/type_blob.reject	2018-01-08 04:21:57.895854615 -0500

@@ -617,7 +617,7 @@

 3	NULL

 explain select * from t1 where txt='Chevy' or txt is NULL;

 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

-1	SIMPLE	t1	ref_or_null	txt_index	txt_index	23	const	2	Using where

+1	SIMPLE	t1	ALL	txt_index	NULL	NULL	NULL	3	Using where

 select * from t1 where txt='Chevy ';

 id	txt

 1	Chevy

mysqltest: Result length mismatch