UnexpectedWireType for Raw batch_put() api

batch_put() api would give the following error:

gRPC error: RpcFailure: 13-INTERNAL Failed to deserialize response message: Codec(WireError(UnexpectedWireType(WireTypeLengthDelimited)))

tikv server: v6.1.3

I also tested tikv v4.0. It does not throw this error.

Example:

use tikv_client::{KvPair, RawClient};

#[tokio::main]
async fn main() -> Result<(), ()> {
    let client = RawClient::new(vec!["127.0.0.1:12379"], None).await.unwrap();
    let kvpair1: KvPair = KvPair("PD".to_owned().into(), "Go".to_owned().into());
    let kvpair2: KvPair = KvPair("TiKV".to_owned().into(), "Rust".to_owned().into());
    let pairs: Vec<KvPair> = vec![kvpair1, kvpair2];

    match client.batch_put(pairs).await {
        Ok(_) => println!("pairs are inserted"),
        Err(e) => println!("error: {}", e),
    };

    Ok(())
}

Output:

Dec 12 10:53:08.427 INFO connect to tikv endpoint: "127.0.0.1:20160"
error: gRPC error: RpcFailure: 13-INTERNAL Failed to deserialize response message: Codec(WireError(UnexpectedWireType(WireTypeLengthDelimited)))

Start with RawClient::batch_put and reproduce the example against TiKV v6.1.3, then compare its response handling with TiKV v4.0. Trace the response deserialization path to identify the incompatible wire type; done means the supplied batch_put example completes without the UnexpectedWireType error.