Random mtr test failures during warning check

galera.galera_unicode_identifiers 'xtradb' w4 [ fail ]
Test ended at 2015-03-21 03:07:37

CURRENT_TEST: galera.galera_unicode_identifiers

Could not execute 'check-warnings' for testcase 'galera.galera_unicode_identifiers' (res: 1) server: 'mysqld.2:
mysqltest: At line 58: query 'call mtr.check_warnings(@result)' failed: 1146: Table 'mtr.error_log' doesn't exist
not ok
mysqltest failed but provided no output
The result from queries just before the failure was:
< snip >
USE `database with space`;
SELECT * FROM `table with space`;
column with space second column with space
1 1
USE `база`;
SELECT * FROM `таблица`;
първа_колона втора_колона
1 1
USE `втора база`;
SELECT * FROM `втора таблица`;
първа колона втора колона
1 1
SET GLOBAL wsrep_sync_wait = (SELECT @@wsrep_sync_wait);
DROP TABLE `database with space`.`table with space`;
DROP TABLE `база`.`таблица`;
DROP TABLE `втора база`.`втора таблица`;
DROP DATABASE `database with space`;
DROP DATABASE `база`;
DROP DATABASE `втора база`;
SET GLOBAL wsrep_sync_wait = (SELECT @@wsrep_sync_wait);

• saving '/run/shm/var/4/log/galera.galera_unicode_identifiers-xtradb/' to '/run/shm/var/log/galera.galera_unicode_identifiers-xtradb/'

Retrying test galera.galera_unicode_identifiers, attempt(2/3)...

worker[4] > Restart - not started
worker[4] > Restart - not started
galera.galera_unicode_identifiers 'xtradb' w4 [ retry-pass ] 16