uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

pkgs/development/python-modules/python-snap7/default.nix

@@ -0,0 +1,46 @@
+{ lib
+, buildPythonPackage
+, snap7
+, fetchFromGitHub
+, setuptools
+, pythonOlder
+}:
+
+buildPythonPackage rec {
+  pname = "python-snap7";
+  version = "1.2";
+  format = "setuptools";
+
+  disabled = pythonOlder "3.6";
+
+  src = fetchFromGitHub {
+    owner = "gijzelaerr";
+    repo = "python-snap7";
+    rev = "refs/tags/${version}";
+    hash = "sha256-xkkJE3wTqS6spwEmQ+HBY1Szao1VFoqmQ041vnAYuqQ=";
+  };
+
+  propagatedBuildInputs = [
+    setuptools
+  ];
+
+  prePatch = ''
+    substituteInPlace snap7/common.py \
+      --replace "lib_location = None" "lib_location = '${snap7}/lib/libsnap7.so'"
+  '';
+
+  # Tests require root privileges to open privilaged ports
+  doCheck = false;
+
+  pythonImportsCheck = [
+    "snap7"
+    "snap7.util"
+  ];
+
+  meta = with lib; {
+    description = "Python wrapper for the snap7 PLC communication library";
+    homepage = "https://github.com/gijzelaerr/python-snap7";
+    license = licenses.mit;
+    maintainers = with maintainers; [ freezeboy ];
+  };
+}