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Technically, the patch is fine and it is the way the code
should have been written in the first place.

Please bring-up on python-dev to determine whether it should
be done.  I can imagine that a fair amount of existing code
has through trial and error discovered the ValueError and
chosen to catch that.  Changing the exception may
unnecessarily break people's code.  Sometimes we  take that
step when it needs to be done, but there should be a good
pay-off and, in this case, I don't see it.

You may also want to mention it on comp.lang.python to see
if anyone cares

If the patch goes forward, see if you can mock-up a test
that triggers the exception so we have a good unittest.

In anycase, this should not be backported (we avoid giving
people reasons to not upgrade).