Implements hook_file_download().
Ensure that user pictures (avatars) are always downloadable.
function user_file_download($uri) {
if (strpos(file_uri_target($uri), variable_get('user_picture_path', 'pictures') . '/picture-') === 0) {
$info = image_get_info($uri);
return array(
'Content-Type' => $info['mime_type'],
);
}
}