[O] babel python example not reproducible

[Shiyuan]

Hi, 

     I try to understand the difference of "session" and "non-session" as in  http://orgmode.org/manual/Results-of-evaluation.html#Results-of-evaluation

However, I copy-paste the example but have different result. It looks like that the result contains whatever sent to the interactive shell too. Any option I need to set to reproduce the same result as in the manual?  I am using python 2.7.5 + emacs 24.3.9 + orgmode 8.2.6. 

#+BEGIN_SRC python :results output :session

 print "hello"

 2

 print "bye"

#+END_SRC

#+RESULTS:

: print "hello"

: hello

: 2

: 2

: print "bye"

: bye

: 

: