Python uuid1 colisions with Ubuntu 12.04 LTS Python 2.7.3

gistfile1.txt

from uuid import uuid1
from time import time

def main():
    test = dict()
    limit = 10 ** 10
    while limit:
        limit -= 1
        x = {n:uuid1().hex for n in range(15)}
        if len(set(x.values())) != len(x.keys()):
            print "Collision"
            return

if __name__ == '__main__':
    start = time()
    main()
    print time() - start