python.pkgs.snowballstemmer: move out of python-packages.nix

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

@@ -0,0 +1,23 @@
+{ stdenv, buildPythonPackage, PyStemmer, fetchPypi }:
+
+buildPythonPackage rec {
+  pname = "snowballstemmer";
+  version = "1.2.1";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "919f26a68b2c17a7634da993d91339e288964f93c274f1343e3bbbe2096e1128";
+  };
+
+  # No tests included
+  doCheck = false;
+
+  propagatedBuildInputs = [ PyStemmer ];
+
+  meta = with stdenv.lib; {
+    description = "16 stemmer algorithms (15 + Poerter English stemmer) generated from Snowball algorithms";
+    homepage = http://sigal.saimon.org/en/latest/index.html;
+    license = licenses.bsd3;
+    platforms = platforms.unix;
+  };
+}

pkgs/top-level/python-packages.nix

@@ -12573,26 +12573,7 @@ in {
     };
   };
 
-  snowballstemmer = buildPythonPackage rec {
+  snowballstemmer = callPackage ../development/python-modules/snowballstemmer { };
-    name = "snowballstemmer-1.2.1";
-
-    src = pkgs.fetchurl {
-      url = "mirror://pypi/s/snowballstemmer/${name}.tar.gz";
-      sha256 = "919f26a68b2c17a7634da993d91339e288964f93c274f1343e3bbbe2096e1128";
-    };
-
-    # No tests included
-    doCheck = false;
-
-    propagatedBuildInputs = with self; [ PyStemmer ];
-
-    meta = {
-      description = "16 stemmer algorithms (15 + Poerter English stemmer) generated from Snowball algorithms";
-      homepage = http://sigal.saimon.org/en/latest/index.html;
-      license = licenses.bsd3;
-      platforms = platforms.unix;
-    };
-  };
 
   spake2 = callPackage ../development/python-modules/spake2 { };