Run a distutils setup script, sandboxed in its directory

def run_setup(setup_script, args):
    """Run a distutils setup script, sandboxed in its directory"""
    setup_dir = os.path.abspath(os.path.dirname(setup_script))
    with setup_context(setup_dir):
        try:
            sys.argv[:] = [setup_script] + list(args)
            sys.path.insert(0, setup_dir)
            # reset to include setup dir, w/clean callback list
            working_set.__init__()
            working_set.callbacks.append(lambda dist: dist.activate())

            # __file__ should be a byte string on Python 2 (#712)
            dunder_file = (
                setup_script
                if isinstance(setup_script, str) else
                setup_script.encode(sys.getfilesystemencoding())
            )

            with DirectorySandbox(setup_dir):
                ns = dict(__file__=dunder_file, __name__='__main__')
                _execfile(setup_script, ns)
        except SystemExit as v:
            if v.args and v.args[0]:
                raise