[jbboehr]

Brings a bunch of fixes to building Rust packages, and it can even be used with the Rust nightly from the Mozilla nixpkgs overlay like this:

    let
	  defaultPkgs = import <nixpkgs> {};
	  defaultRust = defaultPkgs.latest.rustChannels.nightly.rust;
	  defaultCargo = defaultPkgs.latest.rustChannels.nightly.cargo;
	  defaultBuildRustPackage = defaultPkgs.callPackage (import <nixpkgs/pkgs/build-support/rust>) {
		rust = {
			rustc = defaultRust;
			cargo = defaultCargo;
		};
	  };
	in
	  { pkgs ? defaultPkgs, rust ? defaultRust, buildRustPackage ? defaultBuildRustPackage }:

	  pkgs.callPackage ./derivation.nix {
		inherit rust buildRustPackage;
	  }