message: Fix none view_menues.
diff: @@ -66,7 +66,15 @@ OBJECT_SPEC_PERMISSIONS = set([
  def merge_perm(sm, permission_name, view_menu_name):
  - pv = sm.find_permission_view_menu(permission_name, view_menu_name)
  + # Implementation copied from sm.find_permission_view_menu.
  + # TODO: use sm.find_permission_view_menu once issue
  + # https://github.com/airbnb/superset/issues/1944 is resolved.
  + permission = sm.find_permission(permission_name)
  + view_menu = sm.find_view_menu(view_menu_name)
  + pv = None
  + if permission and view_menu:
  + pv = sm.get_session.query(sm.permissionview_model).filter_by(
  + permission=permission, view_menu=view_menu).first()
  if not pv and permission_name and view_menu_name:
  sm.add_permission_view_menu(permission_name, view_menu_name)
  