message: Improve logging message.
diff: @@ -106,7 +106,7 @@ impl<I: Clone + PartialEq + 'static> LinearChainSync<I> {
  highest_block_seen,
  ..
  } => format!(
  - "syncing trusted hash: {:?}, highest block seen: {:?}",
  + "syncing descendants of trusted hash: {:?}, highest block seen: {:?}",
  trusted_hash, highest_block_seen
  ),
  State::SyncingDescendants {
  