I'm not sure it's worth fixing this, but it seems worth recording:

>>> -0.5 // float('inf')
-1.0

I was expecting a value of `-0.0`, and while IEEE 754 doesn't cover the floor division operation, I'm reasonably confident that that's the value it would have recommended if it had. :-)

However, it's difficult to come up with a situation where the difference matters: there aren't any obvious invariants I can think of that are broken by this special case.  So unless anyone thinks it should be changed, I'll settle for recording the oddity in this issue, and closing as won't fix after a short period.