On Fri, Mar 29, 2013 at 11:09 AM, Eric Schulte <schulte.eric@gmail.com> wrote:

Because of quirks of the python language, when executing outside of a
session, it is necessary to explicitly specify a return.
...

This is clearly stated in the Python documentation on Worg.
http://orgmode.org/worg/org-contrib/babel/languages/ob-doc-python.html

... which I just wrote!  Glad it's already useful! :-)

I think in any case you will need my recent patch if you want to use session mode. 

If testing is holding up application of my patch, I can test it on Linux and Mac.

--
Gary