tests.fetchurl: add showURLs-urls-mirrors

    # tarballs.nixos.org, which provides pre-built derivation outputs.

  };

  showURLs-urls-mirrors = testers.invalidateFetcherByDrvHash fetchurl (finalAttrs: {

    name = "test-fetchurl-showURLs-urls-mirrors";

    showURLs = true;

    urls = [

      "http://broken"

    ]

    ++ hello.src.urls;

    hash =

      let

        hashAlgo = lib.head (lib.splitString "-" lib.fakeHash);

      in

      hashAlgo

      + ":"

      + builtins.hashString hashAlgo (

        lib.concatStringsSep " " (lib.concatMap fetchurl.resolveUrl finalAttrs.urls) + "\n"

      );

  });

  urls-simple = testers.invalidateFetcherByDrvHash fetchurl {

    name = "test-fetchurl-urls-simple";

    urls = [