innodb.undo_truncate_recover failed in buildbot with MySQL server has gone away on SHOW VARIABLES

innodb.undo_truncate_recover '16k,2,innodb' w2 [ fail ]

        Test ended at 2018-10-11 20:49:09

CURRENT_TEST: innodb.undo_truncate_recover

mysqltest: In included file "./include/shutdown_mysqld.inc": 

included from D:/win32-debug/build/src/mysql-test/suite/innodb/t/undo_truncate_recover.test at line 45:

At line 40: 'SHOW VARIABLES LIKE 'pid_file'' failed: 2006 MySQL server has gone away

The result from queries just before the failure was:

SET GLOBAL innodb_undo_logs = 4;

SET GLOBAL innodb_undo_log_truncate = 1;

SET GLOBAL innodb_purge_rseg_truncate_frequency = 1;

create table t1(keyc int primary key, c char(100)) engine = innodb;

begin;

commit;

begin;

update t1 set c = 'MariaDB';

update t1 set c = 'InnoDB';

set global debug_dbug = '+d,ib_undo_trunc';

commit;

call mtr.add_suppression("InnoDB: The transaction log size is too large");

SET GLOBAL innodb_fast_shutdown=0;