ob-ruby: clean up the session code some more and work around an I/O sync problem in comint
* lisp/ob-ruby.el (org-babel-ruby-evaluate): Clean up the session code
and remove a superfluous `butlast'. Work around a problem in comint
where the first prompt in a session may be printed after the
evaluation has already started, thus producing a spurious line in
the output.
* testing/lisp/test-ob-ruby.el (test-ob-ruby/session-output-1,
test-ob-ruby/session-output-2 test-ob-ruby/session-output-3): Test
correct transfer of interpreter state across several session
invocations.