clippy::op_ref false positive with deref coercions

[Manishearth]

    let a = "a".to_string();
    let b = "a";

    if b < &a {
        println!("OK");
    }

This warns, but it should not, since the &a is necessary to coerce the type. We even incorrectly test for this case.

[ghost]

Is this the same as #2597?

[Manishearth]

Yep