message: Use the era's earliest block to get activation era validators.
diff: @@ -227,10 +227,14 @@ where
  .expect("missing block in genesis era")
  .state_root_hash()
  } else {
  - // The parent of the first key block contains the activation era validator set.
  - let next_key_block = &key_blocks[&(activation_era_id + 1)];
  + // The first block in the activation era contains the validator set.
  + let block_height = if activation_era_id.is_genesis() {
  + 0
  + } else {
  + &key_blocks[&activation_era_id].height() + 1
  + };
  *effect_builder
  - .get_block_at_height_local(next_key_block.height() - 1)
  + .get_block_at_height_local(block_height)
  .await
  .expect("missing block in activation era")
  .state_root_hash()
  