Random comments from original author of textwrap.py, in case anyone cares at this point...

* This is a pretty obscure edge case, and I admit that it never occurred to me when writing the code. (If it had, I would have tested it!)

* One can debate endlessly about whether this is a bug or not -- witness the recent discussion on this bug. Meh. Not interesting. IMHO it's better described as undefined behaviour. If you want it defined, write tests to enforce the status quo and improve the docs.

* If there is a consensus to change the current behaviour, IMHO it should NOT be done on 2.7. Even if the new behaviour is better by some definition, it's still a behaviour change that could bite someone. Those changes should happen when you make a major upgrade (3.2 to 3.3, say), not when you make a bug fix upgrade (2.7.3 to 2.7.4). IOW: keep it on trunk. Or default, whatever we're calling it these days. ;-)