1. Change code log-slave-updates system variable to work
2. Add Binlog_purge_failed system status variable. So you can monitor this status variable for binary log purge works well or not.
   Binlog_purge_failed=0 : Normal status
   Binlog_purge_failed=1 : PURGE BINLOG command or Automatic binary log purge called with ACTIVE binary log
   Binlog_purge_failed=2 : PURGE BINLOG command or Automatic binary log purge called with IN-USE binary log