mariabackup.full_backup failed in buildbot with timeout

mariabackup.full_backup '16k,innodb'     w4 [ fail ]  timeout after 2700 seconds

        Test ended at 2017-09-12 12:16:31

Test case timeout after 2700 seconds

== D:/winx64-debug/build/mysql-test/var/4/log/full_backup.log == 

CREATE TABLE t(i INT) ENGINE INNODB;

INSERT INTO t VALUES(1);

# xtrabackup backup

INSERT INTO t VALUES(2);

# xtrabackup prepare

# shutdown server

# remove datadir

# xtrabackup move back

# restart server

 == D:/winx64-debug/build/mysql-test/var/4/tmp/analyze-timeout-mysqld.1.err ==

mysqltest: Could not open connection 'default' after 500 attempts: 2002 Can't connect to MySQL server on 'localhost' (10061)