innodb.purge_thread_shutdown failed in buildbot with wrong result (sporadic)

innodb.purge_thread_shutdown 'innodb'    w4 [ fail ]

        Test ended at 2017-09-13 01:37:34

CURRENT_TEST: innodb.purge_thread_shutdown

--- /mnt/buildbot/build/mariadb-10.2.9/mysql-test/suite/innodb/r/purge_thread_shutdown.result	2017-09-13 00:04:28.000000000 +0300

+++ /mnt/buildbot/build/mariadb-10.2.9/mysql-test/suite/innodb/r/purge_thread_shutdown.reject	2017-09-13 01:37:33.000000000 +0300

@@ -5,11 +5,11 @@

 select user,state from information_schema.processlist order by 2;

 user	state

 root	

+system user	closing tables

 root	Filling schema table

 system user	InnoDB purge coordinator

 system user	InnoDB purge worker

 system user	InnoDB purge worker

-system user	InnoDB purge worker

 system user	InnoDB shutdown handler

 set global debug_dbug='+d,only_kill_system_threads';

 set global innodb_fast_shutdown=0;

mysqltest: Result length mismatch