Python MD5 of remote file (URL)

remotemd5.py

import os, hashlib, urllib2, optparse

def get_remote_md5_sum(url, max_file_size=100*1024*1024):
    remote = urllib2.urlopen(url)
    hash = hashlib.md5()

    total_read = 0
    while True:
        data = remote.read(4096)
        total_read += 4096

        if not data or total_read > max_file_size:
            break

        hash.update(data)

    return hash.hexdigest()

if __name__ == '__main__':
    opt = optparse.OptionParser()
    opt.add_option('--url', '-u', default='http://www.google.com')

    options, args = opt.parse_args()
    print get_remote_md5_sum(options.url)

Note to myself: urlopen doesn't work with umlaut in the URL (use request instead)

If I run it on the same url twice it always produces a diff hash, even tho the file did not change. I can't figure out how to fix that. Any help would be appreciated. Or works as designed?