msgpack-rust: Error when deserializing internally-tagged enum

Given an internally-tagged enum with NewType variants, serializing produces a valid value but deserializing fails. For example:

#[derive(Serialize, Deserialize)]
#[serde(tag = "type")]
enum TestEnum {
    Foo(TestType),
    Bar(TestType),
}

#[derive(Serialize, Deserialize)]
struct TestType {
  inner: u32,
}

let test_enum1 = TestEnum::Foo(TestType{inner: 123});
let serialized = rmp_serde::to_vec(&test_enum1).unwrap();
let test_enum2 = rmp_serde::from_slice(&serialized).unwrap();

The serializer produces [146, 163, 70, 111, 111, 123], equivalent to the JSON value ["Foo", 123]. That’s the value I was expecting.

The deserializer fails with the error Syntax("invalid type: sequence, expected any value").

Everything works if I remove the line #[serde(tag = "type")], but then the serializer produces [146, 0, 145, 145, 123], equivalent to the JSON value [0, [[123]]]. If possible I’d prefer to use the internally tagged representation.