py3: add "b" prefix to string literals related to module policy String literals without explicit prefix in __init__.py and policy.py are treated as unicode object on Python3, because these modules are loaded before setup of our specific code transformation (the later module is imported at the beginning of __init__.py). BTW, "modulepolicy" in __init__.py is initialized by "policy.policy". This causes issues below; - checking "policy" value in other modules causes unintentional result For example, "b'py' not in (u'c', u'py')" returns True unintentionally on Python3. - writing "policy" out fails at conversion from unicode to bytes 62939e0148f1 fixed this issue for default code path, but "policy" can be overridden by HGMODULEPOLICY environment variable (it should be rare case for developer using Python3, though). This patch does: - add "b" prefix to all string literals, which are related to module policy, in modules above. - check existence of HGMODULEPOLICY, and overwrite "policy" only if it exists For simplicity, this patch omits checking "supports_bytes_environ", switching os.environ/os.environb, and so on (Yuya agreed this in personal talking)

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# policy.py - module policy logic for Mercurial.

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#

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# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>

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#

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# This software may be used and distributed according to the terms of the

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# GNU General Public License version 2 or any later version.

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from __future__ import absolute_import

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import os

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import sys

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# Rules for how modules can be loaded. Values are:

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#

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#    c - require C extensions

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#    allow - allow pure Python implementation when C loading fails

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#    cffi - required cffi versions (implemented within pure module)

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#    cffi-allow - allow pure Python implementation if cffi version is missing

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#    py - only load pure Python modules

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#

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# By default, require the C extensions for performance reasons.

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policy = b'c'

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policynoc = (b'cffi', b'cffi-allow', b'py')

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policynocffi = (b'c', b'py')

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try:

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    from . import __modulepolicy__

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    policy = __modulepolicy__.modulepolicy

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except ImportError:

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    pass

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# PyPy doesn't load C extensions.

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#

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# The canonical way to do this is to test platform.python_implementation().

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# But we don't import platform and don't bloat for it here.

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if '__pypy__' in sys.builtin_module_names:

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    policy = 'cffi'

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# Our C extensions aren't yet compatible with Python 3. So use pure Python

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# on Python 3 for now.

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if sys.version_info[0] >= 3:

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    policy = b'py'

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# Environment variable can always force settings.

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if sys.version_info[0] >= 3:

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    if 'HGMODULEPOLICY' in os.environ:

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        policy = os.environ['HGMODULEPOLICY'].encode('utf-8')

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else:

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    policy = os.environ.get('HGMODULEPOLICY', policy)