rename() problem with GlusterFS

#!/usr/bin/python

import os
import time
import shutil
import sys


def main():
    source_filename = sys.argv[1]
    destination_filename = sys.argv[2]

    while True:
        print time.time()

        time.sleep(0.05)

        if os.path.isdir(source_filename):
            os.stat(source_filename)
    else:
            continue

    print "moving", source_filename, '->', destination_filename

        os.rename(source_filename, destination_filename)

if __name__ == '__main__':
    main()