Almost all of python makes the abstraction that ints are a single type of thing, the fact that some ints are too big to store in 8 bytes of memory is abstracted away. This abstraction fails when you try to reverse large ranges. 

>>> reversed(range(1<<63))
<longrange_iterator object at 0x7f0925d26660>
>>> reversed(range(1<<63-1))
<range_iterator object at 0x7f0925d26600>
>>> type(reversed(range(1<<63-1)))
<class 'range_iterator'>
>>> type(reversed(range(1<<63)))
<class 'longrange_iterator'>
>>> type(reversed(range(1<<63-2)))==type(reversed(range(1<<63-1)))
True
>>> type(reversed(range(1<<63-1)))==type(reversed(range(1<<63)))
False