Issue #1264208 by lazysoundsystem, Digidog: Fixed recursive serialization of attributes.

link.module

@@ -309,7 +309,9 @@ function _link_process(&$item, $delta = 0, $field, $entity) {
   }
 
   // Serialize the attributes array.
-  $item['attributes'] = serialize($item['attributes']);
+  if (!is_string($item['attributes'])) {
+    $item['attributes'] = serialize($item['attributes']);
+  }
 
   // Don't save an invalid default value (e.g. 'http://').
   if ((isset($field['widget']['default_value'][$delta]['url']) && $item['url'] == $field['widget']['default_value'][$delta]['url'])
@@ -976,4 +978,4 @@ function link_content_migrate_instance_alter(&$instance_value, $field_value) {
  */
 function link_field_settings_form() {
   return array();
-}
\ No newline at end of file
+}