[O] possible bug exporting blocks?

[John Kitchin]

If I export this block to org (C-c C-e O O):

#+begin: exercise
#+ipynb-newcell
*Exercise 1*
#+end

I get this:

#+BEGIN: exercisenil
#+ipynb-newcell
*Exercise 1*
#+END:

there is an extra nil at the end of the first line. That seems like a
bug, does anyone else get this?

I am running org 9.0.5.

Thanks,

-- 
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu