[Guido van Rossum]
Now consider my frustration. We go through a lot of efforts to make consecutive releases backwards compatible, to document changes, to introduce warnings about future incompatible changes, etc.
Yes, I quite understand how frustrating it may be for you, and I do witness the results of all these efforts. The Python documentation is of high quality, rather complete, and very abundant for whoever looks around a tiny bit. In my own experience, migrating has been a breeze all over.
Is it not fair that I ask you to provide more details or shut up?
Not only fair, but also easier: providing details is natural for me! I sometimes fear being perceived as a nit-picker. On one hand, I met many maintainers who like detailed reports on little things! :-). On the other hand, I've seen a few maintainers getting furious, and this is no fun.
[...] most users don't read the manuals even once
You may be right. But then, they miss something! :-)
Example: the possibility to write list.append(a, b, c, ...) was never documented, yet it caused widespread complaints when we disallowed it.
This is frustrating, indeed. Wandering outside specs is a capital sin. (This is why, for example, I find that most current HTML usage is horrible.) I wonder if, in your place, I would be so soft with users :-).
 Don't throw the first stone, they say! For one, I routinely abuse of immediate automatic finalisation in C-Python, but _only_ after Tim told me it will never go away. Still, there is no promise of this in the manual :-).
-- François Pinard http://www.iro.umontreal.ca/~pinard