Can you give me more specific instructions what I need to do
to recreate the issue?

With group, do you mean you have changed one of the keywords via the
webinterface?

What do you mean presicely by getting a unicode string back from the 
form?

If you tried python 2.7.1, do you have a chance to try 2.7.2
as they seems to have fixed a number of issues between 2.7.1 and 2.7.2, 
some even in the io module. But it is hard to say if this affects the 
issue.