For other's reference, there were three threads in November2010 that touch on this:

  :About removing argparse.__all__ or adding more methods to it:
    http://mail.python.org/pipermail/python-dev/2010-November/105147.html

  :Removing tk interface in pydoc:
    http://mail.python.org/pipermail/python-dev/2010-November/105375.html

The most on topic thread is the one with Subject:
  :[Python-Dev] Breaking undocumented API:
    http://mail.python.org/pipermail/python-dev/2010-November/105392.html

People broke threading a few times so you might have to search on the subject.

And ick.  The thread's more of a mess than I remembered.  Reading what Guido wrote last it seems like:

All private names should be prepended with "_" .  Imported modules are the exception to this -- they're private unless included in __all__.  Reading between the lines I think it's also saying that not all public names need to be in __all__.

So to resolve this ticket:

1) Is this the actual consensus from the end of those threads?
2) Are the three names mentioned in this ticket public or private?
3a) If private, initiate deprecation and create underscore versions of the variables.
3b) If public, documentation and adding to __all__ are good but not necessary.