Hi,

Below is a very small patch to Python session blocks, to make them
return a blank result (empty string) instead of None when there is no
return value.

Normally I would push this myself, but since we are so close to 9.4, I
thought it prudent to mail a patch and let the maintainers handle it. It
would be nice to include in 9.4, but not a big deal if I've missed the
window.

Now for an explanation of the patch: 9.4 changes Python session blocks
to fix several bugs and improve robustness overall [0]. However, there
is a cost to these fixes, which is that the session blocks can only
return a result when it is a top-level expression on the last line of
the block. If the last line is not a top-level expression, the block
would previously print "None". However, after some testing, I think this
is a little counter-intuitive, and it would be better if it returned a
blank (empty) result instead of "None".

[0] https://lists.gnu.org/archive/html/emacs-orgmode/2020-01/msg00190.html

Best,
Jack