The Python 2.7 goes even as far as to say that format(1e10, ' ') should give "the same as" format(1e10, ' g') (not something "similar to g"), which is obviously incorrect.

If the Python 3.4 documentation for the empty presentation type of floats were used in the Python 2.7 documentation, it would be closer to the real behavior of Python 2.7, so that would be an improvement.

Now, the real question is whether the Python 3.4 documentation applies exactly to Python 2.7, here, or whether improving the Python 2.7 documentation would require a different description.