Rc<T> does not implement RefUnwindSafe

[mtak-]

Arc<T> implements both UnwindSafe and RefUnwindSafe (though maybe it only gets RefUnwindSafe because all of it's members happen to implement RefUnwindSafe).

Whereas Rc<T> only implements UnwindSafe. This seems like an oversight.

https://play.rust-lang.org/?gist=0d89773218a347569615e1bea7b352f6&version=nightly