[Datetime-SIG] Another round on error-checking

[Ethan Furman]

On 08/31/2015 04:55 PM, Tim Peters wrote:

[...]

> At this point we have:
>
>      u1 == dt1 == dt2 == u2 and u1 < u2
>      hash(dt1) == hash(dt2) == hash(u1)
>
> (Parenthetically, note that despite the chain of equalities in the
> first of those lines, we do _not_ have u1 == u2 - transitivity fails,
> which is a bit of a wart by itself.)

At this point are there any other cases in the stdlib where transitivity fails?  I was under the impression that such cases are to be considered bugs.  I know it was a driving concern in the 
implementation of the enum module.

--
~Ethan~