In issue 5920, Mark Dickinson raises an issue having to do with float.__format__ and how it handles the default format presentation type (that is, none of 'f', 'g', or 'e') versus how str() works on floats: http://bugs.python.org/issue5920

I agree with him that the current behavior is confusing and should be changed. I'm going to make this change, unless anyone objects. Please comment on the issue itself if you have any feedback.

Eric.