[O] recent ESS commit breaks org-babel-R session output capture

[Jack Kamm]

Hello all,

An ESS commit last week broke org-babel-R session output capture. In 
particular, the following no longer works:

#+BEGIN_SRC R :session :results output
  print("hello")
#+END_SRC

The code runs but org-babel fails to capture the output and place it in the 
buffer.

I think the breakage is caused by ESS changing the way it prints prompts ">" 
over multiline input. org-babel was using the prompt to find and strip out 
tokens it inserts, but now can't find the prompt and just strips the whole 
output.

I've posted an issue on the ESS github as well, hopefully the ESS maintainers 
can provide some advice on how to proceed:
https://github.com/emacs-ess/ESS/issues/598

Jack