Poor error message upon running SHOW BINLOG EVENTS on encrypted binlog with a wrong key

• start server with binlog encryption and file_key_management plugin/keyfile;
• create some events;
• restart server with a different keyfile (different value for key 1);
• run SHOW BINLOG EVENTS on the previous log:

MariaDB [test]> show binlog events in 'jessie-bin.000001';

ERROR 1220 (HY000): Error when executing command SHOW BINLOG EVENTS: Wrong offset or I/O error

Naturally, server shouldn't be able to decrypt the binlog, but the diagnostics could have been better.