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/tools/backup/pyznap/default.nix

@@ -0,0 +1,29 @@
+{ lib
+, buildPythonApplication
+, fetchPypi
+, setuptools
+}:
+
+buildPythonApplication rec {
+  pname = "pyznap";
+  version = "1.6.0";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "88bf1d6de2c11f14acbdfa01b61eb95c94f95d829ddebdaee3786b64ccb93ae3";
+  };
+
+  propagatedBuildInputs = [
+    setuptools
+  ];
+
+  # tests aren't included in the PyPI packages
+  doCheck = false;
+
+  meta = {
+    homepage = "https://github.com/yboetz/pyznap";
+    description = "ZFS snapshot tool written in python";
+    license = with lib.licenses; [ gpl3 ];
+    maintainers = with lib.maintainers; [ rbrewer ];
+  };
+}