Inconsistent viewkeys behaviour

[Gregory Ewing]

Terry Reedy wrote:
> The left operand determines the result. The manual specifies that < and 
>  > do not have to be consistent. But I suspect that when 3.x dict.keys() 
> was backported to 2.7.0, no one thought to update set, whereas the 
> backported key view code already had the comparison.

The question is why set() is raising an exception
instead of returning NotImplemented to give the
other operand a chance.

-- 
Greg