python-packages: prompt_toolkit -> 0.40

Fixes:
- Fix in output_screen_diff: reset correctly.
- Ignore flush errors in vt100_output.
- Implemented <num>gg Vi key binding.
- Bug fix in the renderer when the style changes.

New features:
- TokenListControl can now display the cursor somewhere.
- Added SwitchableValidator class.
- print_tokens function added.
- get_style argument for Application added.
- KeyBindingManager got an enable_all argument.

Backwards incompatible changes:
- history_search is now a SimpleFilter instance.

pkgs/top-level/python-packages.nix

@@ -8868,11 +8868,11 @@ let
 
   prompt_toolkit = buildPythonPackage rec {
     name = "prompt_toolkit-${version}";
-    version = "0.39";
+    version = "0.40";
 
     src = pkgs.fetchurl {
+      sha256 = "0zyp2zpbckpdhapijvg7jwli71ilhp02awn99ly70q3l1f44m9dj";
       url = "https://pypi.python.org/packages/source/p/prompt_toolkit/${name}.tar.gz";
-      sha256 = "1046fhgqd1171n8xyzcxwzcxgkcwa77r08g7iih8k5x7z59l94lb";
     };
 
     buildInputs = with self; [ jedi ipython pygments ];