> Is this about correct?  Do any test cases need to be updated or added?  I
> notice that something called BytesIO is imported from io but not used.
 Were
> some test cases removed which used to involve that class or is that a 2to3
> artifact?

The set of test cases is almost exactly parallel between 2.7 and 3.1. 
3.1 adds an additional DictReader test, and refactors one set of tests
to make the code simpler.  Other than that, it is just a matter of
replacing the file opening and closing code that uses binary mode with
'with' statements where the open uses newline=''.  BytesIO is not used
so would appear to be a conversion artifact.