message: Remove linear_chain_block.
diff: @@ -82,8 +82,6 @@ enum State {
  /// Synchronizing the descendants of the trusted hash.
  SyncingDescendants {
  trusted_hash: BlockHash,
  - /// Linear chain block being downloaded.
  - linear_chain_block: Box<Option<BlockHeader>>,
  /// The most recent block we started to execute. This is updated whenever we start
  /// downloading deploys for the next block to be executed.
  latest_block: Box<BlockHeader>,
  @@ -127,7 +125,6 @@ impl State {
  fn sync_descendants(trusted_hash: BlockHash, latest_block: BlockHeader) -> Self {
  State::SyncingDescendants {
  trusted_hash,
  - linear_chain_block: Box::new(None),
  latest_block: Box::new(latest_block),
  highest_block_seen: 0,
  }
  @@ -200,9 +197,7 @@ impl<I: Clone + PartialEq + 'static> LinearChainSync<I> {
  match &mut self.state {
  State::None | State::Done => {}
  State::SyncingTrustedHash { linear_chain, .. } => linear_chain.push(block_header),
  - State::SyncingDescendants {
  - linear_chain_block, ..
  - } => *linear_chain_block = Box::new(Some(block_header)),
  + State::SyncingDescendants { latest_block, .. } => **latest_block = block_header,
  };
  }
  @@ -322,13 +317,13 @@ impl<I: Clone + PartialEq + 'static> LinearChainSync<I> {
  {
  let peer = self.random_peer_unsafe();
  - let next_block = match self.state {
  + let next_block = match &mut self.state {
  State::None | State::Done => {
  panic!("Tried fetching next block when in {:?} state.", self.state)
  }
  State::SyncingTrustedHash {
  - ref mut linear_chain,
  - ref mut latest_block,
  + linear_chain,
  + latest_block,
  ..
  } => match linear_chain.pop() {
  None => None,
  @@ -339,19 +334,7 @@ impl<I: Clone + PartialEq + 'static> LinearChainSync<I> {
  Some(block)
  }
  },
  - State::SyncingDescendants {
  - ref mut linear_chain_block,
  - ref mut latest_block,
  - ..
  - } => match linear_chain_block.take() {
  - None => None,
  - Some(block) => {
  - // Update `latest_block` so that we can verify whether result of execution
  - // matches the expected value.
  - **latest_block = block.clone();
  - Some(block)
  - }
  - },
  + State::SyncingDescendants { latest_block, .. } => Some((**latest_block).clone()),
  };
  next_block.map_or_else(
  