tests.fetchgit: pass `system` and the existing `config`

{

  stdenv,

  config,

  runCommand,

  testers,

  fetchgit,

  withGitConfig =

    let

      pkgs = import ../../.. {

        config.gitConfig = {

        system = stdenv.hostPlatform.system;

        config = config // {

          gitConfig = {

            url."https://github.com".insteadOf = "https://doesntexist.forsure";

          };

        };

      };

    in

    pkgs.testers.invalidateFetcherByDrvHash pkgs.fetchgit {

      name = "fetchgit-with-config";