ISLANDORA-317: fixed by checking the stuff.

fedora_repository.module

@@ -752,6 +752,10 @@ function fedora_repository_get_items($pid = NULL, $dsId = NULL, $collection = NU
     return '';
   }
   
+  if ($pid == NULL) {
+    $pid = variable_get('fedora_repository_pid', 'islandora:top');
+  }
+
   $item = new fedora_item($pid);
   if (!$item->exists()) {
     drupal_not_found();