get_children() doesn't support 'fields' => 'ids' as an argument

[danielbachhuber]

Not sure whether it should, but it would be nice.

When you pass 'fields' => 'ids' as an argument, the data returned by get_posts() is nooped with this block:

foreach ( $children as $key => $child )
    $kids[$child->ID] = $children[$key];

I've added a patch that checks whether the fields parameter is set to either ids or id=>parent, in which case it returns the result from get_posts. Please note that if this is the case, the $output parameter will have no effect. This is something to consider, as it does make the functionality a bit confusing.

Another option would be to ignore the fields parameter for this function and add documentation for that, but it does break functionality currently.