message: [cluster-test] exclude seed node val-0 from twin list
  Closes:
  Approved by: andll
diff: @@ -37,14 +37,18 @@ pub struct TwinValidators {
  impl ExperimentParam for TwinValidatorsParams {
  type E = TwinValidators;
  fn build(self, cluster: &Cluster) -> Self::E {
  - if self.pair > 3 {
  - panic!("pair number {} can not more than 9", self.pair);
  + if self.pair >= cluster.validator_instances().len() {
  + panic!(
  + "pair number {} can not equal or more than validator number {}",
  + self.pair,
  + cluster.validator_instances().len()
  + );
  }
  let mut instances = cluster.validator_instances().to_vec();
  let mut twin_validators = vec![];
  let mut rnd = rand::thread_rng();
  for _i in 0..self.pair {
  - twin_validators.push(instances.remove(rnd.gen_range(0, instances.len())));
  + twin_validators.push(instances.remove(rnd.gen_range(1, instances.len())));
  }
  Self::E {
  instances,
  