Don't change local behavior with app cache

If you cache git remotes (`bundle package --all`), and then change the version you are locked to, bundler will do a fresh checkout of the repo into the `app_cache_path` instead of using the one that is already in the global `cache_path` (because `set_local!` overrides `cache_path`).

I can't figure out what the reason is for calling `set_local!` if it is cached.