I admit that the docs for 2.5 lack explicitness in this aspect. It is not explicitly said that fileobj may be passed without a name argument. However, in the method signature name is listed as optional. If no name argument is passed I would say behaviour is *undefined* atm. I may be too pedantic, but:

1. It is perfectly simple to work around this problem.
2. It is just a question of code-niceness.
3. It is already fixed for the next major release.

I do not like to take the risk to break someone's code with a bugfix release.