commit 732e769257f84788b3ce89121b1dac79ee5f8972
Author: Joel Pittet <joel@pittet.ca>
Date:   Sun May 3 13:58:10 2015 -0700

    default parameters

diff --git a/modules/product/commerce_product.module b/modules/product/commerce_product.module
index 5bcb166..6653804 100644
--- a/modules/product/commerce_product.module
+++ b/modules/product/commerce_product.module
@@ -727,7 +727,7 @@ function commerce_product_set_properties($product, $name, $value) {
  * The values returned will be keyed by SKU and appear as such in the textfield,
  * even though the preview in the autocomplete list shows "SKU: Title".
  */
-function commerce_product_autocomplete($entity_type, $field_name, $bundle, $string = '') {
+function commerce_product_autocomplete($entity_type = '', $field_name = '', $bundle = '', $string = '') {
   if (empty($entity_type) || empty($field_name) || empty($bundle)) {
     return MENU_NOT_FOUND;
   }