mariabackup --help only lists server groups read in configuration

$ extra/mariabackup/mariabackup --help --verbose

Open source backup tool for InnoDB and XtraDB

Copyright (C) 2009-2015 Percona LLC and/or its affiliates.

Portions Copyright (C) 2000, 2011, MySQL AB & Innobase Oy. All Rights Reserved.

This program is free software; you can redistribute it and/or

modify it under the terms of the GNU General Public License

as published by the Free Software Foundation version 2

of the License.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You can download full text of the license on http://www.gnu.org/licenses/gpl-2.0.txt

Usage: extra/mariabackup/mariabackup [--defaults-file=#] [--backup | --prepare | --copy-back | --move-back] [OPTIONS]

Default options are read from the following files in the given order:

/etc/my.cnf /etc/mysql/my.cnf ~/.my.cnf 

The following groups are read: mysqld server mysqld-10.4 mariadb mariadb-10.4 mariadbd mariadbd-10.4 client-server galera