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/purepng/default.nix

@@ -0,0 +1,48 @@
+{ lib
+, buildPythonPackage
+, python
+, fetchFromGitHub
+, fetchpatch
+, cython ? null
+, numpy ? null
+}:
+
+buildPythonPackage {
+  pname = "purepng";
+  version = "0.2.0";
+
+  src = fetchFromGitHub {
+    owner = "Scondo";
+    repo = "purepng";
+    rev = "449aa00e97a8d7b8a200eb9048056d4da600a345";
+    sha256 = "105p7sxn2f21icfnqpah69mnd74r31szj330swbpz53k7gr6nlsv";
+  };
+
+  patches = [
+    (fetchpatch {
+      name = "fix-py37-stopiteration-in-generators.patch";
+      url = "https://github.com/Scondo/purepng/pull/28/commits/62d71dfc2be9ffdc4b3e5f642af0281a8ce8f946.patch";
+      sha256 = "1ag0pji3p012hmj8kadcd0vydv9702188c0isizsi964qcl4va6m";
+    })
+  ];
+  patchFlags = [ "-p1" "-d" "code" ];
+
+  # cython is optional - if not supplied, the "pure python" implementation will be used
+  nativeBuildInputs = [ cython ];
+
+  # numpy is optional - if not supplied, tests simply have less coverage
+  checkInputs = [ numpy ];
+  # checkPhase begins by deleting source dir to force test execution against installed version
+  checkPhase = ''
+    rm -r code/png
+    ${python.interpreter} code/test_png.py
+  '';
+
+  meta = with lib; {
+    description = "Pure Python library for PNG image encoding/decoding";
+    homepage    = "https://github.com/scondo/purepng";
+    license     = licenses.mit;
+    maintainers = with maintainers; [ ris ];
+  };
+
+}