These callsites either used `vec![..]` instead of a static slice `[..]`
or, worse, collected into a Vec unnecessarily. The refactor in the
parent commit to `IntoIterator<Item = String>` for `Registers::write`
makes these Vecs unnecessary as the values are appended to each register
via `VecDeque::extend`.
We could take this change further by returning the number of values we
yanked in `Registers::write`. However this would only remove the need
to collect from one callsite, so this further refactor is deferred until
it would more useful in the future.