problem with $dest param to file_save_upload()

Hi,

I'm in the process of converting the Avatar Selection module to Drupal 6.x. In it I want to use the file_save_upload() function but I'm having problems with the $dest parameter. The api documentation says:

file_save_upload($source, $validators = array(), $dest = FALSE, $replace = FILE_EXISTS_RENAME)
....
$dest A string containing the directory $source should be copied to. If this is not provided, the temporary directory will be used.

To me this sounds like I can set the $dest variable to be a path to a directory, so my code is :

$dest_dir = file_create_path('avatar_selection');
$validators = array(
  'file_validate_is_image' => array(),
  'file_validate_image_resolution' => array(variable_get('user_picture_dimensions', '85x85')),
  'file_validate_size' => array(variable_get('user_picture_file_size', '30') * 1024),
);

$file = file_save_upload('picture_upload', $validators, $dest_dir, FILE_EXISTS_RENAME);

However, this gives me the following errors:

* warning: move_uploaded_file(files/travel-with-me.eu/avatar_selection) [function.move-uploaded-file]: failed to open stream: Is a directory in /var/www/drupal_6.1_20070904/html/includes/file.inc on line 570.
* warning: move_uploaded_file() [function.move-uploaded-file]: Unable to move '/tmp/phpcaqh3S' to 'files/travel-with-me.eu/avatar_selection' in /var/www/drupal_6.1_20070904/html/includes/file.inc on line 570.
* File upload error. Could not move uploaded file.

I think this is because the move_uploaded_file() expects its destination param to be the path to a file, not a directory. The file_save_upload() function doesn't modify the dest param if it's already set and so this function only works if (a) no destination param is provided or (b) if the destination provided is a file, not a directory.

Whichever way you look at it, this is a bug. Either the file_save_upload() function should be changed so it can update the destination to be a path to the file (based on supplied $dest) or the documentation should be updated so it correctly defines the $dest param.

Cheers,
Stella