message: Fix booking block height calculation
diff: @@ -220,8 +220,12 @@ where
  fn booking_block_height(&self, era_id: EraId) -> u64 {
  // The booking block for era N is the last block of era N - AUCTION_DELAY - 1
  // To find it, we get the start height of era N - AUCTION_DELAY and subtract 1
  - let after_booking_era_id =
  - EraId(era_id.0.saturating_sub(self.protocol_config.auction_delay));
  + let after_booking_era_id = EraId(
  + era_id
  + .0
  + .saturating_sub(self.protocol_config.auction_delay)
  + .max(self.protocol_config.last_activation_point.0),
  + );
  self.active_eras
  .get(&after_booking_era_id)
  .expect("should have era after booking block")
  