Options with negative stock value are not removed [PATCH]

An attribute with a negative stock value is not removed from the list. This simple patch fixes that:

--- a/sites/all/modules/uc_attribute_stock_filter/uc_attribute_stock_filter.module
+++ b/sites/all/modules/uc_attribute_stock_filter/uc_attribute_stock_filter.module
@@ -88,7 +88,7 @@ function uc_attribute_stock_filter_form_alter(&$form, $form_state, $form_id) {
       $available = array();
       while ($data = db_fetch_object($result)) {
         $combo = unserialize($data->combination);
-        if ($data->stock || !$data->active) { // Stock is available or stock tracking is NOT active
+        if ($data->stock > 0 || !$data->active) { // Stock is available or stock tracking is NOT active
           $available = array_merge($available, array_values($combo)); // Merge value into array
         }
       }