safe_mutex: Trying to lock unitialized mutex was issued after rpl.rpl_test_framework in buildbot

rpl.rpl_test_framework 'stmt'            w1 [ pass ]   6510

worker[1] > Restart [mysqld.1 - pid: 15626, winpid: 15626] - using different config file

worker[1] > Restart [mysqld.2 - pid: 15627, winpid: 15627] - using different config file

worker[1] > Restart [mysqld.3 - pid: 15631, winpid: 15631] - using different config file

worker[1] > Restart [mysqld.4 - pid: 15634, winpid: 15634] - using different config file

worker[1] > Restart [mysqld.5 - pid: 15637, winpid: 15637] - using different config file

worker[1] > Restart [mysqld.6 - pid: 15641, winpid: 15641] - using different config file

worker[1] > Restart [mysqld.7 - pid: 15645, winpid: 15645] - using different config file

worker[1] > Restart [mysqld.8 - pid: 15648, winpid: 15648] - using different config file

worker[1] > Restart [mysqld.9 - pid: 15651, winpid: 15651] - using different config file

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

safe_mutex: Trying to lock unitialized mutex at /opt/buildbot-slave/mariadb/dan_demeter1/build/sql/sql_plugin.cc, line 3112

Attempting backtrace. You can use the following information to find out