Index: modules/field/field.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.module,v
retrieving revision 1.18
diff -u -r1.18 field.module
--- modules/field/field.module	11 Jul 2009 00:56:45 -0000	1.18
+++ modules/field/field.module	13 Jul 2009 03:34:54 -0000
@@ -270,14 +270,15 @@
  */
 function field_set_empty($field, $items) {
   // Filter out empty values.
-  $filtered = array();
   $function = $field['module'] . '_field_is_empty';
-  foreach ((array) $items as $delta => $item) {
-    if (!$function($item, $field)) {
-      $filtered[] = $item;
+  if (drupal_function_exists($function)) {
+    foreach ((array) $items as $delta => $item) {
+      if ($function($item, $field)) {
+        unset($items[$delta]);
+      }
     }
   }
-  return $filtered;
+  return $items;
 }
 
 /**