Return the checksum of the current thin tarball

def thin_sum(cachedir, form='sha1'):
    '''
    Return the checksum of the current thin tarball
    '''
    thintar = gen_thin(cachedir)
    code_checksum_path = os.path.join(cachedir, 'thin', 'code-checksum')
    if os.path.isfile(code_checksum_path):
        with salt.utils.files.fopen(code_checksum_path, 'r') as fh:
            code_checksum = "'{0}'".format(fh.read().strip())
    else:
        code_checksum = "'0'"

    return code_checksum, salt.utils.hashutils.get_hash(thintar, form)