Mariadb-dump --delete-master-logs May Not Delete Binary Logs

Because --delete-master-logs immediately purges logs after flushing, if there are any active dump threads on the master, they may still be using the old binary log when the purge executes, disallowing the file from being deleted.

Workarounds are either to manually re-run PURGE BINARY LOGS TO once the dump threads have caught up, or to temporarily disconnect replicas before performing the dump.

Test case 8 in mysql-test/main/rpl_mysqldump_slave.test implements the second work-around for consistent behavior to pass. Depending on the resolution of this ticket, that test may need to be fixed to remove the work-around.