message: Log instance ID when starting an era.
diff: @@ -221,7 +221,7 @@ where
  &mut self,
  era_id: EraId,
  timestamp: Timestamp,
  - validator_stakes: Vec<(PublicKey, Motes)>,
  + mut validator_stakes: Vec<(PublicKey, Motes)>,
  newly_slashed: Vec<PublicKey>,
  seed: u64,
  start_time: Timestamp,
  @@ -232,12 +232,15 @@ where
  panic!("{} already exists", era_id);
  }
  self.current_era = era_id;
  + let instance_id = instance_id(&self.chainspec, state_root_hash, start_height);
  + validator_stakes.sort();
  info!(
  ?validator_stakes,
  %start_time,
  %timestamp,
  %start_height,
  + %instance_id,
  era = era_id.0,
  "starting era",
  );
  @@ -271,7 +274,7 @@ where
  .and_then(|last_era_id| self.active_eras.get(&last_era_id));
  let mut consensus = (self.new_consensus)(
  - instance_id(&self.chainspec, state_root_hash, start_height),
  + instance_id,
  validator_stakes,
  &slashed,
  &self.chainspec,
  