@staticmethod
def get_build_id(filename, env_name):
    """
        Extract build id from the file name
        In downloader.py, we have the following name convenion
             local_fn = u'{}-{}.{}'.format(self._build_name, self._build, extension)
        """
    prefix = '{0}-'.format(env_name)
    if filename.startswith(prefix) and '.' in filename:
        return True, filename[len(prefix):filename.index('.')]
    return False, None
