Message 65704 - Python tracker

This has nothing to do with set.update, the difference is due to the
time to setup the generator:

$ python -m timeit -s 'x = set(range(10000)); y = []' 'x.update(y)'
1000000 loops, best of 3: 0.38 usec per loop
$ python -m timeit -s 'x = set(range(10000)); y = (i for i in [])'
'x.update(y)'
1000000 loops, best of 3: 0.335 usec per loop