python.pkgs.unifi: move to separate expression

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

···
+{ stdenv, buildPythonPackage
+, fetchPypi, urllib3 }:
+
+buildPythonPackage rec {
+  pname = "unifi";
+  version = "1.2.5";
+  name = "${pname}-${version}";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "0prgx01hzs49prrazgxrinm7ivqzy57ch06qm2h7s1p957sazds8";
+  };
+
+  propagatedBuildInputs = [ urllib3 ];
+
+  # upstream has no tests
+  doCheck = false;
+
+  meta = with stdenv.lib; {
+    description = "An API towards the Ubiquity Networks UniFi controller";
+    homepage    = https://pypi.python.org/pypi/unifi/;
+    license     = licenses.mit;
+    maintainers = with maintainers; [ peterhoeg ];
+  };
+}

pkgs/top-level/python-packages.nix

···
     hdf5 = pkgs.hdf5.override { zlib = pkgs.zlib; };
   };
 
-  unifi = buildPythonPackage rec {
-    name = "unifi-1.2.5";
-
-    propagatedBuildInputs = with self; [ urllib3 ];
-
-    # upstream has no tests
-    doCheck = false;
-
-    meta = {
-      description = "An API towards the Ubiquity Networks UniFi controller";
-      homepage    = https://pypi.python.org/pypi/unifi/;
-      license     = licenses.mit;
-      maintainers = with maintainers; [ peterhoeg ];
-    };
-
-    src = pkgs.fetchurl {
-      url = "mirror://pypi/u/unifi/${name}.tar.gz";
-      sha256 = "0prgx01hzs49prrazgxrinm7ivqzy57ch06qm2h7s1p957sazds8";
-    };
-  };
+  unifi = callPackage ../development/python-modules/unifi { };
 
   pyunbound = callPackage ../tools/networking/unbound/python.nix { };