binlog_encryption.rpl_parallel failed in buildbot, timeout, assertion `count > 0' failed

binlog_encryption.rpl_parallel 'innodb_plugin,stmt' w1 [ fail ]  timeout after 900 seconds

        Test ended at 2017-11-02 23:23:26

Test case timeout after 900 seconds

== /mnt/buildbot/build/mariadb-10.1.29/mysql-test/var/1/log/rpl_parallel.log == 

64	64

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SET debug_sync='RESET';

SET debug_sync='now SIGNAL d0_cont';

SET debug_sync='now WAIT_FOR t1_waiting';

SET debug_sync='now SIGNAL d3_cont';

SET debug_sync='now WAIT_FOR t2_waiting';

SET debug_sync='now SIGNAL d1_cont';

SET debug_sync='now WAIT_FOR t3_waiting';

SET debug_sync='now SIGNAL d2_cont';

SET debug_sync='now WAIT_FOR t4_waiting';

KILL THD_ID;

SET debug_sync='now WAIT_FOR t3_killed';

SET debug_sync='now SIGNAL t1_cont';

include/wait_for_slave_sql_error.inc [errno=1317,1927,1964]

 == /mnt/buildbot/build/mariadb-10.1.29/mysql-test/var/1/tmp/analyze-timeout-mysqld.2.err ==

mysqltest: Could not open connection 'default' after 500 attempts: 2002 Can't connect to local MySQL server through socket '/mnt/buildbot/build/mariadb-10.1.29/mysql-test/var/tmp/1/mysqld.2.sock' (111 "Connection refused")

 == /mnt/buildbot/build/mariadb-10.1.29/mysql-test/var/1/tmp/analyze-timeout-mysqld.1.err ==

mysqltest: Could not open connection 'default' after 500 attempts: 2002 Can't connect to local MySQL server through socket '/mnt/buildbot/build/mariadb-10.1.29/mysql-test/var/tmp/1/mysqld.1.sock' (111 "Connection refused")