The devguide [1] currently says:
It’s unlikely bug fixes will require a Contributor Licensing Agreement unless they touch a lot of code. For new features, it is preferable to ask that the contributor submit a signed CLA to the PSF as the associated comments, docstrings and documentation are far more likely to reach a copyrightable standard.
Is this still the case?
No. IANAL, but I think the proper requirement is that there must be some creative act in writing the code (such as naming an identifier). If the work is under copyright (which isn't up to the author to decide), then we need the form from the author.
How about new features that are quite small? (e.g. http://bugs.python.org/issue14809 whose patch adds a few constants from a newer RFC)
It's probably a border case, as anybody would have likely come up with roughly the same patch. Still, I would have put EungJun Yi into Misc/ACKS (for doing the research), and asked him for a contributor form.
If we are to require a signed agreement from smaller changes too, the devguide should be updated.
Will do!
Regards, Martin