encryption.encrypt_and_grep failed in buildbot with wrong result (sporadic)

encryption.encrypt_and_grep 'cbc,innodb' w4 [ fail ]

        Test ended at 2017-09-08 05:21:32

CURRENT_TEST: encryption.encrypt_and_grep

--- /mnt/buildbot/build/mariadb-10.2.9/mysql-test/suite/encryption/r/encrypt_and_grep.result	2017-09-08 01:57:14.000000000 +0300

+++ /mnt/buildbot/build/mariadb-10.2.9/mysql-test/suite/encryption/r/encrypt_and_grep.reject	2017-09-08 05:21:32.000000000 +0300

@@ -14,11 +14,8 @@

 test/t3

 SELECT NAME FROM INFORMATION_SCHEMA.INNODB_TABLESPACES_ENCRYPTION WHERE MIN_KEY_VERSION <> 0;

 NAME

-mysql/innodb_table_stats

-mysql/innodb_index_stats

 test/t1

 test/t2

-innodb_system

 # t1 yes on expecting NOT FOUND

 NOT FOUND /foobarsecret/ in t1.ibd

 # t2 ... on expecting NOT FOUND

@@ -30,10 +27,16 @@

 # Now turn off encryption and wait for threads to decrypt everything

 SET GLOBAL innodb_encrypt_tables = off;

 # Wait max 10 min for key encryption threads to decrypt all spaces

+Timeout in wait_condition.inc for SELECT COUNT(*) = 5 FROM INFORMATION_SCHEMA.INNODB_TABLESPACES_ENCRYPTION WHERE MIN_KEY_VERSION = 0 AND CURRENT_KEY_VERSION = 0;

+Id	User	Host	db	Command	Time	State	Info	Progress

+1	system user		NULL	Daemon	NULL	InnoDB purge coordinator	NULL	0.000

+2	system user		NULL	Daemon	NULL	InnoDB purge worker	NULL	0.000

+3	system user		NULL	Daemon	NULL	InnoDB purge worker	NULL	0.000

+4	system user		NULL	Daemon	NULL	InnoDB purge worker	NULL	0.000

+5	system user		NULL	Daemon	NULL	InnoDB shutdown handler	NULL	0.000

+8	root	localhost	test	Query	0	init	show full processlist	0.000

 SELECT NAME FROM INFORMATION_SCHEMA.INNODB_TABLESPACES_ENCRYPTION WHERE MIN_KEY_VERSION = 0;

 NAME

-mysql/innodb_table_stats

-mysql/innodb_index_stats

 test/t2

 test/t3

 innodb_system

mysqltest: Result length mismatch