message: docs: last_common_header
diff: @@ -41,6 +41,8 @@ impl BlockFetcher {
  let last_common_header = {
  if let Some(header) = self.synchronizer.peers().get_last_common_header(self.peer) {
  Some(header)
  + // Bootstrap quickly by guessing a parent of our best tip is the forking point.
  + // Guessing wrong in either direction is not a problem.
  } else if best.number() < self.snapshot.tip_header().number() {
  let last_common_hash = self.snapshot.store().get_block_hash(best.number())?;
  self.snapshot.store().get_block_header(&last_common_hash)
  @@ -49,6 +51,8 @@ impl BlockFetcher {
  }
  }?;
  + // If the peer reorganized, our previous last_common_header may not be an ancestor
  + // of its current tip anymore. Go back enough to fix that.
  let fixed_last_common_header = self
  .snapshot
  .last_common_ancestor(&last_common_header, &best.inner())?;
  