message: Fix StateProof logic around expected value for GET_REV_REG_DELTA request.
diff: @@ -418,16 +418,16 @@ fn _parse_reply_for_multi_sp(_json_msg: &SJsonValue, data: Option<&str>, parsed_
  let multi_signature = parsed_data["stateProofFrom"]["multi_signature"].clone();
  let value_str = if !parsed_data["value"]["accum_from"].is_null() {
  - json!({
  + Some(json!({
  "lsn": parsed_data["value"]["accum_from"]["seqNo"],
  "lut": parsed_data["value"]["accum_from"]["txnTime"],
  "val": parsed_data["value"]["accum_from"],
  - }).to_string()
  + }).to_string())
  } else {
  - return Err("No accum_from value".to_string());
  + None
  };
  - (proof.to_owned(), root_hash.to_owned(), multi_signature, Some(value_str))
  + (proof.to_owned(), root_hash.to_owned(), multi_signature, value_str)
  }
  constants::GET_REVOC_REG_DELTA => return Ok(None),
  _ => {
  