[issue8425] a -= b should be fast if a is a small set and b is a large set

[Michele Orrù]

Michele Orrù added the comment:

Something like this would also need unit tests?

$ ./python.exe -m timeit -s "s= set(range(2000)); l = set(range(20000000)); s=s-l"
10000000 loops, best of 3: 0.0622 usec per loop
[48787 refs]
$ ./python.exe -m timeit -s "s= set(range(2000)); l = set(range(20000000)); s-=l"
10000000 loops, best of 3: 0.0591 usec per loop
[48787 refs]

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Added file: http://bugs.python.org/file27265/issue8425.patch

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