self: super:
let
  checkInputsAreNative = self.lib.hasInfix "nativeCheckInputs"
    (builtins.readFile <nixpkgs/doc/stdenv/stdenv.chapter.md>);
  checkInputsName =
    if checkInputsAreNative then "nativeCheckInputs" else "checkInputs";

  fallback-git-cache = self.python3Packages.callPackage
    ({ buildPythonPackage, fetchgit, git, backoff, mypy, }:
      buildPythonPackage rec {
        pname = "git-cache";
        version = "1.4.3";
        src = fetchgit {
          url = "https://git.scottworley.com/pub/git/git-cache";
          rev = "v${version}";
          hash = "sha256-Qr62bGdlFFkzYTl6ot34UiOJxbP1Eeelx2OEd96vrqI=";
        };
        propagatedBuildInputs = [ backoff ];
        "${checkInputsName}" = [ git mypy ];
        doCheck = true;
        checkPhase = "./test.sh";
      }) { };

  fallback-pinch = self.python3Packages.callPackage
    ({ buildPythonPackage, fetchgit, nix_2_3, git, makeWrapper, mypy, git-cache, }:
      buildPythonPackage rec {
        pname = "pinch";
        version = "3.0.15";
        src = fetchgit {
          url = "https://git.scottworley.com/pub/git/pinch";
          rev = "v${version}";
          hash = "sha256-dOTX1UHnQb7GCO5iFZfl+GDf+kpnRZpzhjuTy9aw7DA=";
        };
        buildInputs = [ makeWrapper ];
        propagatedBuildInputs = [ git-cache ];
        "${checkInputsName}" = [ nix_2_3 git mypy ];
        postInstall = ''
          wrapProgram "$out/bin/pinch" --prefix PATH : ${nix_2_3}/bin
        '';
        doCheck = true;
        checkPhase = "./test.sh";
      }) { git-cache = self.python3Packages.git-cache or fallback-git-cache; };

in { pinch = super.pinch or fallback-pinch; }