Python 3 __cmp__ semantic change?

[Terry Reedy]

Ben Finney wrote:
> Steve Holden <steve at holdenweb.com> writes:
> 
>> You will observe that __cmp__ no longer appears in the index:
>>
>> http://docs.python.org/dev/3.0/genindex-_.html
> 
> I searched in vain for an official description of this changed
> behaviour. Where can we find an official description of how
> comparisons are different in Python 3.0?

I was going to say "look in "What's New", but the __cmp__ removal is 
missing.  So I filed
http://bugs.python.org/issue4372