DockerTools Problem

docker.nix

{ pkgs ? import <nixpkgs> {} }: with pkgs.dockerTools;

let
  someBaseImage = pullImage {
    imageName = "nixos/nix";
    imageDigest = "sha256:1b97dc98b599779d80271d4203275627c0749d8bd5e9b9c868154249395cbc1b";
    sha256 = "134h20xgpqchcvgv0f13knsi2p7jfl4m9mk8hkvdgh8hnz0hj3hc";
  };
in
buildImage {
  name = "test";
  fromImage = someBaseImage;
  contents = with pkgs; [ coreutils bash ];
  config = {
    Cmd = [ "bash" ];
  };
  runAsRoot = ''
    #!${pkgs.stdenv.shell}
    echo WORKS
  '';
}