[PATCH 1 of 2] demandimport: alias __builtin__ as builtins

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1435451355 25200
#      Sat Jun 27 17:29:15 2015 -0700
# Node ID 9f0cea1d292415d264798752fdc5bbe658b9b5e0
# Parent  ff5172c830022b64cc5bd1bae36b2276e9dc6e5d
demandimport: alias __builtin__ as builtins

Python 3 renamed the __builtin__ module to builtins. In preparation for
supporting Python 3, alias the imported module as "builtins."

diff --git a/mercurial/demandimport.py b/mercurial/demandimport.py
--- a/mercurial/demandimport.py
+++ b/mercurial/demandimport.py
@@ -23,10 +23,11 @@ These imports will not be delayed:
   from a import *
   b = __import__(a)
 '''
 
-import __builtin__, os, sys
+import os, sys
 from contextlib import contextmanager
+import __builtin__ as builtins
 
 _origimport = __import__
 
 nothing = object()
@@ -35,9 +36,9 @@ try:
     # Python 3 doesn't have relative imports nor level -1.
     level = -1
     if sys.version_info[0] >= 3:
         level = 0
-    _origimport(__builtin__.__name__, {}, {}, None, level)
+    _origimport(builtins.__name__, {}, {}, None, level)
 except TypeError: # no level argument
     def _import(name, globals, locals, fromlist, level):
         "call _origimport with no level argument"
         return _origimport(name, globals, locals, fromlist)
@@ -170,18 +171,18 @@ ignore = [
     'distutils.msvc9compiler'
     ]
 
 def isenabled():
-    return __builtin__.__import__ == _demandimport
+    return builtins.__import__ == _demandimport
 
 def enable():
     "enable global demand-loading of modules"
     if os.environ.get('HGDEMANDIMPORT') != 'disable':
-        __builtin__.__import__ = _demandimport
+        builtins.__import__ = _demandimport
 
 def disable():
     "disable global demand-loading of modules"
-    __builtin__.__import__ = _origimport
+    builtins.__import__ = _origimport
 
 @contextmanager
 def deactivated():
     "context manager for disabling demandimport in 'with' blocks"