Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 15)
+++ wp-includes/functions.php	(working copy)
@@ -3284,14 +3284,15 @@
  * @return array
  */
 function wp_list_pluck( $list, $field ) {
+	$ret = array();
 	foreach ( $list as $key => $value ) {
 		if ( is_object( $value ) )
-			$list[ $key ] = $value->$field;
+			$ret[ $key ] = $value->$field;
 		else
-			$list[ $key ] = $value[ $field ];
+			$ret[ $key ] = $value[ $field ];
 	}
 
-	return $list;
+	return $ret;
 }
 
 /**