connection_options made mandatory for non default connection

I just tested new 7.x-1.0-rc1 and noticed that it has made having connection_options in configuration mandatory.

README.txt gives an example and says that connection_options might be used. Out of this I got the impression that they are not mandatory. So I have used configuration like:

$conf['mongodb_connections'] = array(
    'default' => array('host' => 'localhost', 'db' => 'sitename'),
);

After installing the rc1 I got fatal error "unsupported operand types" from mongodb/mongodb.module line 30. The system is trying to have union with non-existing connection_options.