[rustc_data_structures] Simplify SortedMap::insert. It looks like current usage of `swap` is aimed at achieving what `std::mem::replace` does but more concisely and idiomatically.
[rustc_data_structures] Simplify SortedMap::insert. It looks like current usage of `swap` is aimed at achieving what `std::mem::replace` does but more concisely and idiomatically.