message: Only retire backup when test suite can progress
diff: @@ -120,11 +120,13 @@ def test_add_node_untrusted_code(network, args):
  @reqs.description("Retiring a backup")
  @reqs.at_least_n_nodes(2)
  +@reqs.can_kill_n_nodes(1)
  def test_retire_backup(network, args):
  primary, _ = network.find_primary()
  backup_to_retire = network.find_any_backup()
  network.consortium.retire_node(primary, backup_to_retire)
  backup_to_retire.stop()
  + check_can_progress(primary)
  return network
  