For example (noticing the last line '#+end_example' is not indented with
two space)

* test
  #+BEGIN_SRC sh :results output
  seq 10
  #+END_SRC

  #+RESULTS:
  #+begin_example
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
#+end_example


By reading the source code, I think 'indent-rigidly' doesn't the correct
end bound so the last line is not indented

(defun org-babel-insert-result (result &optional result-params info hash lang)
  ...
  (org-babel-examplify-region beg end results-switches inline)
  (setq end (point))
  ...
  (indent-rigidly beg end indent)
  ...
  )

'org-babel-examplify-region' wraps the result within
#+begin_example..#+end_example but doesn't move the point forward by one
line because of using save-excursion.

I attach a patch which uses the marker 'end' to track where the result
block ends, instead of (point). I have tested it against Emacs
24.5 and 25.2 slightly.