>> I disagree that this is release-critical. I think it is desirable to
>> say that the dbm modules support most of a dict-style interface,
>> and I also think that it is factually correct to claim that they
>> currently do.
> 
> Supporting only __getitem__, __setitem__, __delitem__, __contains__ and
> keys is already "most of a dict-style interface"? 

It's also __len__... Indeed, I think that this is the major part of the
dict interface. For a number of additional methods, it would be
straight-forward to support them as well (such as get(), pop(),
popitem(), setdefault(), update()). That they are missing should be
considered as a regular bug/missing feature. However, it appears that
nobody has complained about those missing features in all these years,
so that they are missing can't be that serious.

> However, for the dbm modules I would be in favor of only specifying the
> four mentioned methods, as in the docstring of dbm/__init__.py, and not
> claiming any more.

I don't mind the documentation to explain precisely what is, as long as
it continues to explain what could be.