Is there a document which lists these things, and explains how it is desirable to communicate them? I recently updated Twisted's equivalent document, adding minutae like which buttons to click on in our issue tracker, since that seems obvious to me but apparently wasn't obvious to a lot of new contributors.
I'm not quite sure whether this is what you are asking for, but there is http://www.python.org/dev/workflow/
My reading of it suggests that he was saying "netaddr appears to be superior in every way, so python should include that instead. But, if someone is insisting on ipaddr here are the things that could change about it". The important thing here is that interpretation of the comment is required, so I can definitely see how you saw it the way you did. There is no "-1" in his comment, and there's no documentation (that I'm aware of) which says that a "-1" is required, or how it will be used or interpreted.
Well, there is http://www.python.org/dev/peps/pep-0010/ I personally use them sometimes, but wouldn't insist on others using them. Regards, Martin