TaggedValue is not preserved by to_value

[dtolnay]

use serde::Serialize;

#[derive(Serialize)]
enum Enum {
    Variant(usize),
}

fn main() {
    let value = serde_yaml::to_value(&Enum::Variant(0)).unwrap();
    println!("{:#?}", value);

    let value: serde_yaml::Value = serde_yaml::from_value(value).unwrap();
    println!("{:#?}", value);

    let value = serde_yaml::to_value(&value).unwrap();
    println!("{:#?}", value);
}

TaggedValue {
    tag: !Variant,
    value: Number(0),
}
TaggedValue {
    tag: !Variant,
    value: Number(0),
}
Mapping {
    "!Variant": Number(0),
}