message: Add comments, remove unnecessary logic.
diff: @@ -636,9 +636,6 @@ fn valid_booking_block(
  let after_booking_era_id = era_id
  .saturating_sub(auction_delay)
  .max(last_activation_point);
  - if after_booking_era_id.is_genesis() {
  - return None;
  - }
  // If we would have gone below the last activation point (which can be Genesis era or the
  // first era after an upgrade), we return `None` as there are no booking blocks there that
  // we can use.
  @@ -658,18 +655,19 @@ async fn collect_booking_block_hashes<REv>(
  where
  REv: From<StorageRequest>,
  {
  - let (no_booking_block_eras, other_eras): (Vec<EraId>, Vec<EraId>) =
  + let (no_booking_block_eras, eras_with_booking_blocks): (Vec<EraId>, Vec<EraId>) =
  era_ids.into_iter().partition(|era_id| {
  valid_booking_block(&era_id, auction_delay, last_activation_point).is_none()
  });
  + // For those eras we wouldn't have the booking block, so we use a "zero" one.
  let mut booking_block_hashes: HashMap<EraId, BlockHash> = no_booking_block_eras
  .iter()
  .map(|era_id| (*era_id, BlockHash::default()))
  .collect();
  let booking_blocks = effect_builder
  - .collect_booking_blocks(other_eras)
  + .collect_booking_blocks(eras_with_booking_blocks)
  .await
  .expect("should have all booking blocks in the storage");
  