Download the cdiff files

def download_diffs(queue):
    """Download the cdiff files"""
    while True:
        options, signature_type, localver, remotever = queue.get()
        for num in range(int(localver), int(remotever) + 1):
            sig_diff = '%s-%d' % (signature_type, num)
            filename = os.path.join(options.mirrordir, '%s.cdiff' % sig_diff)
            if not os.path.exists(filename):
                update_diff(options, sig_diff)
        queue.task_done()