factorio: use real instead of sample in download help; warn about credentials in store (#351555)

  mods = args.mods or [ ];

  helpMsg = ''

  helpMsg =

    { dlName, storeName }:

    ''

      ===FETCH FAILED===

      Please ensure you have set the username and token with config.nix, or

      /etc/nix/nixpkgs-config.nix if on NixOS.

    Your token can be seen at https://factorio.com/profile (after logging in). It is

    not as sensitive as your password, but should still be safeguarded. There is a

    link on that page to revoke/invalidate the token, if you believe it has been

    leaked or wish to take precautions.

      Your token can be seen at https://factorio.com/profile (after logging in).

      Beware this will add the credentials to the Nix store, which is

      world-readable on the local machine. It is not as sensitive as your

      password, but should still be safeguarded. There is a link on that page to

      revoke/invalidate the token, if you believe it has been leaked or wish to

      take precautions.

      Example:

      {

      download the release through https://factorio.com/download , then add it to

      the store using e.g.:

      releaseType=alpha

      version=0.17.74

      nix-prefetch-url file://\''$HOME/Downloads/factorio_\''${releaseType}_x64_\''${version}.tar.xz --name factorio_\''${releaseType}_x64-\''${version}.tar.xz

    Note the ultimate "_" is replaced with "-" in the --name arg!

        nix-prefetch-url file://\''$HOME/Downloads/${dlName} --name ${storeName}

      If you go this route you might want to tell Nix to explicitly hold on to the

      source tarball. Otherwise it could get GC'd from the Nix store and you'd

                  '';

              failureHook = ''

                cat <<EOF

                ${helpMsg}

                ${helpMsg {

                  dlName = if candidateHashFilenames != [ ] then builtins.head candidateHashFilenames else name;

                  storeName = name;

                }}

                EOF

              '';

            })