libxslt: build python bindings

and add a pythonPackages.libxslt alias.

pkgs/development/libraries/libxslt/default.nix

@@ -1,4 +1,9 @@
-{ stdenv, fetchurl, fetchpatch, libxml2, findXMLCatalogs }:
+{ stdenv, fetchurl, fetchpatch, libxml2, findXMLCatalogs
+, pythonSupport ? true, python2
+}:
+
+assert pythonSupport -> python2 != null;
+assert pythonSupport -> libxml2.pythonSupport;
 
 stdenv.mkDerivation rec {
   name = "libxslt-1.1.29";
@@ -10,26 +15,33 @@ stdenv.mkDerivation rec {
 
   patches = stdenv.lib.optional stdenv.isSunOS ./patch-ah.patch;
 
-  outputs = [ "bin" "dev" "out" "doc" ];
+  outputs = [ "bin" "dev" "out" "doc" ] ++ stdenv.lib.optional pythonSupport "py";
 
-  buildInputs = [ libxml2 ];
+  buildInputs = [ libxml2.dev ] ++ stdenv.lib.optionals pythonSupport [ libxml2.py python2 ];
 
   propagatedBuildInputs = [ findXMLCatalogs ];
 
   configureFlags = [
-    "--without-python"
     "--without-crypto"
     "--without-debug"
     "--without-mem-debug"
     "--without-debugger"
-  ];
+  ] ++ stdenv.lib.optional pythonSupport "--with-python=${python2}";
 
   postFixup = ''
     moveToOutput bin/xslt-config "$dev"
     moveToOutput lib/xsltConf.sh "$dev"
     moveToOutput share/man/man1 "$bin"
+  '' + stdenv.lib.optionalString pythonSupport ''
+    mkdir -p $py/nix-support
+    echo ${libxml2.py} >> $py/nix-support/propagated-native-build-inputs
+    moveToOutput lib/python2.7 "$py"
   '';
 
+  passthru = {
+    inherit pythonSupport;
+  };
+
   meta = with stdenv.lib; {
     homepage = http://xmlsoft.org/XSLT/;
     description = "A C library and tools to do XSL transformations";

pkgs/top-level/python-packages.nix

@@ -13447,6 +13447,9 @@ in {
     clblas = pkgs.clblas-cuda;
   };
 
+  libxslt = if isPy3k then throw "libxslt not supported for interpreter ${python.executable}" else
+    (pkgs.libxslt.override{pythonSupport=true; python2=python; inherit (self) libxml2;}).py;
+
   limnoria = buildPythonPackage rec {
     name = "limnoria-${version}";
     version = "2016.05.06";