Fix interactive function pickling

Author: ogrisel

cloudpickle/cloudpickle.py

@@ -621,11 +621,15 @@ def save_global(self, obj, name=None, pack=struct.pack):
         dispatched here.
         """
         try:
-            return Pickler.save_global(self, obj, name=name)
+            if obj.__module__ == "__main__":
+                raise ValueError("%r is defined in __main__" % obj)
+            else:
+                return Pickler.save_global(self, obj, name=name)
         except Exception:
             if obj.__module__ == "__builtin__" or obj.__module__ == "builtins":
                 if obj in _BUILTIN_TYPE_NAMES:
-                    return self.save_reduce(_builtin_type, (_BUILTIN_TYPE_NAMES[obj],), obj=obj)
+                    return self.save_reduce(
+                        _builtin_type, (_BUILTIN_TYPE_NAMES[obj],), obj=obj)
 
             typ = type(obj)
             if typ is not obj and isinstance(obj, (type, types.ClassType)):