Ihor,

Thank you for investigating, explaining, and also fixing the problem!  I
pulled the latest 'main' and everything works a bit, it seems.

Then, to avoid walking in circles, I decided to write some tests, for I
think shell blocks should never, never, never break in such basic ways,
let alone in production Emacs.

Please, see the WIP patch attached to this message.

I noticed that the following tests do not pass:

1. ob-shell/error-output-after-success

   We seem to trash error output, such as warnings, on success.  I think
   we should not do this.  Now, on the execution of "echo X &>2", Org
   says "Code block produced no output."  But that does hold true.  The
   block did produce output, just on the other output stream, namely
   error output.

2. ob-shell/error-output-after-failure

   We seem not to show the exit code in this case.  Why?

3. ob-shell/exit-codes

   Should we add a newline after the exit code message?

Rudy