mercurial/policy.py

bugzilla: add a rest api backend (usable with bugzilla 5.0+)

Add support for the bugzilla rest api documented at
 https://wiki.mozilla.org/Bugzilla:REST_API
and at
 https://bugzilla.readthedocs.io/en/latest/

This backend has the following benefits:
* It supports the bugzilla api keys so hgrc does not need to contain
  a user's bugzilla password
* Works with Mercurial's "hostfingerprints" support making handling
  bugzilla instances with self-signed certs easier
* Does not use xmlrpc ;-)

Adds configuration item 'apikey' in [bugzilla] section.

My major concern with these patches is if the approach to HTTP access
is the right way for an extension and if hooking into request object
and the overriding the get_method to perform PUT requests was a
sensible approach.

# no-check-commit

# policy.py - module policy logic for Mercurial.
#
# Copyright 2015 Gregory Szorc <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import os
import sys

# Rules for how modules can be loaded. Values are:
#
#    c - require C extensions
#    allow - allow pure Python implementation when C loading fails
#    cffi - required cffi versions (implemented within pure module)
#    cffi-allow - allow pure Python implementation if cffi version is missing
#    py - only load pure Python modules
#
# By default, require the C extensions for performance reasons.
policy = 'c'
policynoc = ('cffi', 'cffi-allow', 'py')
policynocffi = ('c', 'py')

try:
    from . import __modulepolicy__
    policy = __modulepolicy__.modulepolicy
except ImportError:
    pass

# PyPy doesn't load C extensions.
#
# The canonical way to do this is to test platform.python_implementation().
# But we don't import platform and don't bloat for it here.
if '__pypy__' in sys.builtin_module_names:
    policy = 'cffi'

# Our C extensions aren't yet compatible with Python 3. So use pure Python
# on Python 3 for now.
if sys.version_info[0] >= 3:
    policy = 'py'

# Environment variable can always force settings.
policy = os.environ.get('HGMODULEPOLICY', policy)