Array overwriting in ArrayUtils::merge()

If you want to overwrite default value of *baz* array:
``` php 
'foo' => array(
    'bar' => array(
        'baz' => array(
            'dev',
        )
    ),
),
```
by this local version:
```php
'foo' => array(
    'bar' => array(
        'baz' => array(
            'local',
        )
    ),
),
```
on default you get:
```php
'foo' => array(
    'bar' => array(
        'baz' => array(
            0 => 'dev',
            1 => 'local',
        )
    ),
),
```

So the question is, how can I overwrite this value? Without this fix I can't, can I?