Disable ordering on .add-row.

adminsortable/static/adminsortable/css/admin.sortable.inline.css

@@ -1,4 +1,3 @@
-.tabular .sortable
-{
+.tabular .sortable:not(.add-row) {
     cursor: move;
 }

adminsortable/static/adminsortable/js/admin.sortable.tabular.inlines.js

@@ -7,7 +7,7 @@ jQuery(function($){
             axis : 'y',
             containment : 'parent',
             tolerance : 'pointer',
-            items : 'tr',
+            items : 'tr:not(.add-row)',
             stop : function(event, ui)
             {
                 var indexes = Array();