python2Packages.cytoolz: disable

no longer compatibled with python2

```
    File "cytoolz/itertoolz.pyx", line 15, in init cytoolz.itertoolz
      from itertools import chain, islice, zip_longest
  ImportError: cannot import name zip_longest
```

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

@@ -6,20 +6,19 @@
 , toolz
 , python
 , fetchpatch
+, isPy27
 }:
 
 buildPythonPackage rec {
   pname = "cytoolz";
   version = "0.11.0";
+  disabled = isPy27 || isPyPy;
 
   src = fetchPypi {
     inherit pname version;
     sha256 = "c64f3590c3eb40e1548f0d3c6b2ccde70493d0b8dc6cc7f9f3fec0bb3dcd4222";
   };
 
-  # Extension types
-  disabled = isPyPy;
-
   checkInputs = [ nose ];
   propagatedBuildInputs = [ toolz ];