'Build one wheel.
:return: The filename of the built wheel, or None if the build failed.'

def _build_one(self, req, output_dir, python_tag=None):

    tempd = tempfile.mkdtemp('pip-wheel-')
    try:
        if self.__build_one(req, tempd, python_tag=python_tag):
            try:
                wheel_name = os.listdir(tempd)[0]
                wheel_path = os.path.join(output_dir, wheel_name)
                shutil.move(os.path.join(tempd, wheel_name), wheel_path)
                logger.info('Stored    in    directory:    %s', output_dir)
                return wheel_path
            except:
                pass
        self._clean_one(req)
        return None
    finally:
        rmtree(tempd)
