Ticket #19274: 19274.diff

wp-admin/widgets.php

@@ -74 +74 @@
                         'before_title' => '',
                         'after_title' => '',
                 ));
+        } elseif ( empty( $wp_registered_sidebars[ $sidebar_id ] ) ) {
+                unset( $sidebars_widgets[ $sidebar_id ] );
         }
 }