You seem to be implying that some projects may release separate source distributions. I cannot imagine why somebody would want to do that.
That's odd. I can't imagine why anybody would *not* want to do that. Given the number of issues 2to3 can't fix (because it would be too dangerous to guess)
Like which one specifically?
, I certainly can't imagine a just-in-time porting solution that would work reliably.
I can imagine that absolutely.
Making two releases means I can migrate once and only once and be done with it.
No, you won't be done. You have to maintain two releases in parallel now.
Making a single release work on 2.x and 3.x means I have to keep all of the details of both Python 2 and 3 in my head all the time as I code? not to mention litter my codebase with "# the following ugly hack lets us work with Python 2 and 3" comments so someone else doesn't undo all my hard work when they run the tests on Python 3 but not 2? No thanks. My brain is too small.
So you rather put more work into maintenance sequentially. Fair enough. Regards, Martin