main.innodb_ext_key fails sporadically

main.innodb_ext_key 'innodb'             w4 [ fail ]

        Test ended at 2020-04-01 20:19:02

CURRENT_TEST: main.innodb_ext_key

--- /buildbot/ubuntu-1604/build/mysql-test/main/innodb_ext_key.result	2020-04-01 19:39:45.000000000 +0000

+++ /buildbot/ubuntu-1604/build/mysql-test/main/innodb_ext_key.reject	2020-04-01 20:19:02.155337769 +0000

@@ -1014,7 +1014,7 @@

 ORDER BY rev_timestamp ASC LIMIT 10;

 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

 1	SIMPLE	t1	const	PRIMARY,name_title	name_title	261	const,const	1	

-1	SIMPLE	t2	ref	page_timestamp	page_timestamp	4	const	10	Using where

+1	SIMPLE	t2	ALL	page_timestamp	NULL	NULL	NULL	45	Using where; Using filesort

 1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.rev_text_id	1	

 set optimizer_switch='extended_keys=on';

 EXPLAIN 

@@ -1023,7 +1023,7 @@

 ORDER BY rev_timestamp ASC LIMIT 10;

 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

 1	SIMPLE	t1	const	PRIMARY,name_title	name_title	261	const,const	1	

-1	SIMPLE	t2	ref	page_timestamp	page_timestamp	4	const	10	Using where

+1	SIMPLE	t2	ALL	page_timestamp	NULL	NULL	NULL	45	Using where; Using filesort

 1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.rev_text_id	1	

 DROP TABLE t1,t2,t3;

 #