Buildbot tests fail with warnings on server shutdown after rpl.rpl_row_mysqlbinlog

rpl.rpl_row_mysqlbinlog 'row'            [ pass ]   1672

worker[1] > Restart [mysqld.1 - pid: 8517, winpid: 8517] - running with different options '--log-bin=master-bin --log-bin=master-bin --binlog-format=row --max_allowed_packet=1024 --net_buffer_length=1024' != '--log-bin=master-bin --binlog-format=row --log-bin=master-bin --max-binlog-size=1040384'

worker[1] > Restart [mysqld.2 - pid: 8519, winpid: 8519] - running with different options '--log-bin=slave-bin --log-bin=slave-bin --binlog-format=row --max_allowed_packet=1024 --net_buffer_length=1024 --slave_max_allowed_packet=1024' != '--log-bin=slave-bin --binlog-format=row --log-bin=slave-bin'

***Warnings generated in error logs during shutdown after running tests: rpl.rpl_row_mysqlbinlog

161211 11:37:51 [Warning] /private/var/lib/buildslave/maria-slave/labrador/build/sql/mysqld: Forcing close of thread 10  user: 'root'