message: [sync]fix find ancestor.
diff: @@ -489,8 +489,6 @@ where
  break;
  }
  }
  - } else {
  - return Err(format_err!("{:?}", "find ancestor is none."));
  }
  } else {
  return Err(format_err!("{:?}", "block header is none."));
  @@ -728,6 +726,9 @@ where
  .await;
  if end || hash_with_number.is_some() {
  + if end && hash_with_number.is_none() {
  + return Err(format_err!("{:?}", "find ancestor is none."));
  + }
  break;
  }
  } else {
  