global: use python3 in shebangs
Python 3 is the future. We want Python scripts to be using Python 3
by default.
This change updates all `#!/usr/bin/env python` shebangs to use
`python3`.
Does this mean all scripts use or require Python 3: no.
In the test environment, the `PATH` environment variable in tests is
updated to guarantee that the Python executable used to run
run-tests.py is used. Since test scripts all now use
`#!/usr/bin/env python3`, we had to update this code to install
a `python3` symlink instead of `python`.
It is possible there are some random scripts now executed with the
incorrect Python interpreter in some contexts. However, I would argue
that this was a pre-existing bug: we should almost always be executing
new Python processes using the `sys.executable` from the originating
Python script, as `python` or `python3` won't guarantee we'll use the
same interpreter.
Differential Revision: https://phab.mercurial-scm.org/D9273
#!/usr/bin/env python3
#
# 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
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)
from hgdemandimport import tracing
with tracing.log('hg script'):
# 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()