Cannot uncheck active trail checkbox on pane config

When adding a menu block to a panels page, if "Make the starting level follow the active menu item. " is selected it can never be unselected. I believe it is due to the code here:

    127 function menu_block_menu_tree_content_type_edit_form_submit(&$form, &$form_state) {
    128   foreach (array_keys($form_state['subtype']['defaults']) as $key) {
    129     if (!empty($form_state['values'][$key])) {
    130       $form_state['conf'][$key] = $form_state['values'][$key];
    131    }
    132   }
    133 }

Line 129 will exclude updates from unchecked items.