fix pythonDocs install path

pkgs/development/interpreters/python/docs/2.7-html.nix

@@ -2,7 +2,7 @@
 
 { stdenv, fetchurl }:
 
-stdenv.mkDerivation {
+stdenv.mkDerivation rec {
   name = "python27-docs-html-2.7.3";
   src = fetchurl {
     url = http://docs.python.org/ftp/python/doc/2.7.3/python-2.7.3-docs-html.tar.bz2;
@@ -10,6 +10,6 @@ stdenv.mkDerivation {
   };
   installPhase = ''
     mkdir -p $out/share/docs
-    cp -R ./ $out/share/docs/
+    cp -R ./ $out/share/docs/${name}
   '';
 }