Nightly Rust development with devenv

Creating a Nix shell for Rust development is easy if you’re prepared to either use only stable Rust or use Rustup to manage your Rust toolchain. But the latest version of Bevy was not compatible with stable Rust at the time of writing, and using Rustup would sacrifice one of the biggest advantages of Nix: having reproducibility managed by a single component. I’m pretty happy with what I ended up…