Comment 0 for bug 907964

Most of client programs shipped with MariaDB 5.2 / 5.3 do not accept the plugin-dir as an option, which makes authentication that requires a client plugin impossible if the plugin is not in the default folder.

Examples: mysqladmin, mysqldump, etc.
If you decide to change it, please also include mysqlslap into the list, it might be handy for testing sometimes.