capybara/virtualenv/lib/python2.7/site-packages/pip/wheel.py
def _build_one(self, req, output_dir):
        """Build one wheel.

        :return: The filename of the built wheel, or None if the build failed.
        """
        tempd = tempfile.mkdtemp('pip-wheel-')
        try:
            if self.__build_one(req, tempd):
                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:
                    return None
            return None
        finally:
            rmtree(tempd)
def _build_one(self, req, output_dir):
        """Build one wheel.

        :return: The filename of the built wheel, or None if the build failed.
        """
        tempd = tempfile.mkdtemp('pip-wheel-')
        try:
            if self.__build_one(req, tempd):
                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:
                    return None
            return None
        finally:
            rmtree(tempd)
Build one wheel.

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