message: fix: get_ancestor consistent
diff: @@ -93,19 +93,6 @@ impl<CS: ChainStore> ChainProvider for Shared<CS> {
  }
  fn get_ancestor(&self, base: &H256, number: BlockNumber) -> Option<Header> {
  - // if base in the main chain
  - if let Some(n_number) = self.store.get_block_number(base) {
  - if number > n_number {
  - return None;
  - } else {
  - return self
  - .store
  - .get_block_hash(number)
  - .and_then(|hash| self.store.get_block_header(&hash));
  - }
  - }
  -
  - // if base in the fork
  if let Some(header) = self.store.get_block_header(base) {
  let mut n_number = header.number();
  let mut index_walk = header;
  