Error round-tripping complex struct

[casey]

I ran into a problem deserializing a complex struct:

fn ser_de_field_vec_tuple() {
    #[derive(Deserialize, Serialize, Eq, PartialEq, Debug)]
    struct Foo {
        bar: Vec<(u16,)>,
    }

    let foo = Foo {
        bar: vec![(1,), (3,)],
    };

    test_ser_de_eq(foo);
}

The error message is InvalidType("Invalid Type: sequence (expected: field identifier)")'

I wasn't able reduce the test case by removing the struct, the vec, or the tuple, so it seems to be some weird combination of the three.

[0xcaff]

I wonder whether this happens with nested Vecs also. Will take a look eventually maybe.