[PATCH 2 of 5 V2] demandimport: add __future__ to ignore list

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1439079157 25200
#      Sat Aug 08 17:12:37 2015 -0700
# Node ID 4bb6021564277224c09f2a9ea63249af7b33876d
# Parent  4c1a937f7837d4dab00d1ab555ae6f53c2739eaf
demandimport: add __future__ to ignore list

__future__ is special. We should definitely not be trying to lazy
load it.

diff --git a/mercurial/demandimport.py b/mercurial/demandimport.py
--- a/mercurial/demandimport.py
+++ b/mercurial/demandimport.py
@@ -144,8 +144,9 @@ def _demandimport(name, globals=None, lo
                 setattr(mod, x, _demandmod(x, mod.__dict__, locals))
         return mod
 
 ignore = [
+    '__future__',
     '_hashlib',
     '_xmlplus',
     'fcntl',
     'win32com.gen_py',