--- original/locale.install	2007-06-17 19:41:40.000000000 +0200
+++ locale.install	2007-08-25 01:22:56.000000000 +0200
@@ -88,6 +88,7 @@ function locale_update_6002() {
       db_add_column($ret, 'locales_source', 'textgroup', 'varchar(255)', array('default' => "''", 'not null' => TRUE));
       break;
   }
+  $ret[] = update_sql("UPDATE {locales_source} SET textgroup = 'default' WHERE textgroup = ''");
   return $ret;
 }