Babel : python generate org source block with an extra comma before * characters

[Roland DONAT <roland.donat@gmail.com>]

Dear Orgmode community,

Thanks in advance to take some time to help me with my problem...

Here is what is making me very sad :

I have a python (python 3 interpreter) source block that I use to generate 
parts of a report written in Orgmode. Suppose we have this little example :

#+NAME: test
#+BEGIN_SRC python :results value org :session test

report = """*** header 1
My pretty report

*** header 2
Ah ah! With that stuff, I will increase my *productivity*!!!
"""

report
#+END_SRC

What I get is :
#+RESULTS: test
#+BEGIN_SRC org
,*** header 1
My pretty report

,*** header 2
Ah ah, with that stuff, I will increase my *productivity*!!!
#+END_SRC

My question : Why Orgmode adds the comma before the star character???

In the manual, I read some things about comma-escaping in Org source block 
so my intuition tells me that my problem has something to do with that but I 
wasn't able to solve it for now.

My configuration :
- Org 8.2.5h on Linux Mint 16. 
- Python 3

Any help would be much appreciated! Thanks.

Roland.