setup: only allow Python 3 from a source checkout (issue5804)
People are running `pip install Mercurial` with Python 3 and that
is working because not everything performs a Python version
compatibility check.
Modern versions of pip do recognize the "python_requires" keyword
(https://packaging.python.org/tutorials/distributing-packages/#python-requires)
which we set if using setuptools. But this isn't set nor recognized
everywhere.
To prevent people from accidentally installing Mercurial with Python
3 until Python 3 is officially supported, have setup.py fail when
run with Python 3. But don't fail if we're running from a source
checkout, as we don't want to anger Mercurial developers hacking
on Python 3 nor Mercurial's test automation running from source
checkouts. People running setup.py from source checkouts could still
fall through a Python 3 crack. But at least the
`pip install Mercurial` attempt will get nipped in the bud.
#!/usr/bin/env python
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# 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
if os.environ.get('HGUNICODEPEDANTRY', False):
try:
reload(sys)
sys.setdefaultencoding("undefined")
except NameError:
pass
libdir = '@LIBDIR@'
if libdir != '@' 'LIBDIR' '@':
if not os.path.isabs(libdir):
libdir = os.path.join(os.path.dirname(os.path.realpath(__file__)),
libdir)
libdir = os.path.abspath(libdir)
sys.path.insert(0, libdir)
# enable importing on demand to reduce startup time
try:
if sys.version_info[0] < 3 or sys.version_info >= (3, 6):
import hgdemandimport; hgdemandimport.enable()
except ImportError:
sys.stderr.write("abort: couldn't find mercurial libraries in [%s]\n" %
' '.join(sys.path))
sys.stderr.write("(check your install and PYTHONPATH)\n")
sys.exit(-1)
from mercurial import dispatch
dispatch.run()