message: utilise the new_ledger to check the date
diff: @@ -256,10 +256,10 @@ impl Ledger {
  });
  }
  - if date <= self.date {
  + if date <= new_ledger.date {
  return Err(Error::NonMonotonicDate {
  block_date: date,
  - chain_date: self.date,
  + chain_date: new_ledger.date,
  });
  }
  