pythonPackages.purepng: refactor move to python-modules

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

@@ -0,0 +1,21 @@
+{ stdenv
+, buildPythonPackage
+, fetchPypi
+}:
+
+buildPythonPackage rec {
+  pname = "purepng";
+  version = "0.2.0";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "1kcl7a6d7d59360fbz2jwfk6ha6pmqgn396962p4s62j893d2r0d";
+  };
+
+  meta = with stdenv.lib; {
+    description = "Pure Python library for PNG image encoding/decoding";
+    homepage    = https://github.com/scondo/purepng;
+    license     = licenses.mit;
+  };
+
+}

pkgs/top-level/python-packages.nix

@@ -3461,21 +3461,7 @@ in {
 
   pyplatec = callPackage ../development/python-modules/pyplatec { };
 
-  purepng = buildPythonPackage rec {
+  purepng = callPackage ../development/python-modules/purepng { };
-    name = "purepng-${version}";
-    version = "0.2.0";
-
-    src = pkgs.fetchurl {
-      url = "mirror://pypi/p/purepng/${name}.tar.gz";
-      sha256 = "1kcl7a6d7d59360fbz2jwfk6ha6pmqgn396962p4s62j893d2r0d";
-    };
-
-    meta = {
-      description = "Pure Python library for PNG image encoding/decoding";
-      homepage    = https://github.com/scondo/purepng;
-      license     = licenses.mit;
-    };
-  };
 
   pymaging = buildPythonPackage rec {
     name = "pymaging-unstable-2016-11-16";