steam: made update-runtime.py nicer

pkgs/games/steam/update-runtime.py

@@ -1,5 +1,6 @@
-#!/usr/bin/env python2
-#
+#! /usr/bin/env nix-shell
+#! nix-shell -i python2 -p "with python2Packages; [python debian]"
+
 # Script to build a Nix script to actually build a Steam runtime.
 # Patched version of https://github.com/ValveSoftware/steam-runtime/blob/master/build-runtime.py
 
@@ -20,7 +21,7 @@ REPO="http://repo.steampowered.com/steamrt"
 DIST="scout"
 COMPONENT="main"
 
-out = open("runtime-generated.nix", "w");
+out = open("runtime-generated.nix", "w")
 out.write("# This file is autogenerated! Do not edit it yourself, use update-runtime.py for regeneration.\n")
 out.write("{ fetchurl }:\n")
 out.write("\n")