demandimport: drop Py3 workarounds from Py2 implementation

hgdemandimport/demandimportpy2.py

@@ -26,27 +26,17 b' These imports will not be delayed:'
 
 from __future__ import absolute_import
 
+import __builtin__ as builtins
 import contextlib
 import os
 import sys
 
-# __builtin__ in Python 2, builtins in Python 3.
-try:
-    import __builtin__ as builtins
-except ImportError:
-    import builtins
-
 contextmanager = contextlib.contextmanager
 
 _origimport = __import__
 
 nothing = object()
 
-# Python 3 doesn't have relative imports nor level -1.
-level = -1
-if sys.version_info[0] >= 3:
-    level = 0
-
 def _hgextimport(importfunc, name, globals, *args, **kwargs):
     try:
         return importfunc(name, globals, *args, **kwargs)
@@ -172,7 +162,7 b' class _demandmod(object):'
 
 _pypy = '__pypy__' in sys.builtin_module_names
 
-def _demandimport(name, globals=None, locals=None, fromlist=None, level=level):
+def _demandimport(name, globals=None, locals=None, fromlist=None, level=-1):
     if locals is None or name in ignore or fromlist == ('*',):
         # these cases we can't really delay
         return _hgextimport(_origimport, name, globals, locals, fromlist, level)

tests/test-check-py3-compat.t

@@ -3,8 +3,9 b''
   $ . "$TESTDIR/helpers-testrepo.sh"
   $ cd "$TESTDIR"/..
 
-  $ testrepohg files 'set:(**.py)' | sed 's|\\|/|g' \
-  > | xargs $PYTHON contrib/check-py3-compat.py
+  $ testrepohg files 'set:(**.py)' \
+  > -X hgdemandimport/demandimportpy2.py \
+  > | sed 's|\\|/|g' | xargs $PYTHON contrib/check-py3-compat.py
   contrib/python-zstandard/setup.py not using absolute_import
   contrib/python-zstandard/setup_zstd.py not using absolute_import
   contrib/python-zstandard/tests/common.py not using absolute_import
@@ -24,6 +25,7 b''
 
 #if py3exe
   $ testrepohg files 'set:(**.py) - grep(pygments)' \
+  > -X hgdemandimport/demandimportpy2.py \
   > -X hgext/fsmonitor/pywatchman \
   > | sed 's|\\|/|g' | xargs $PYTHON3 contrib/check-py3-compat.py \
   > | sed 's/[0-9][0-9]*)$/*)/'