[O] diff in `src' blocks

[Oliver Večerník]

Hi,

in the following org file the second block gets not exported (tested with
text and html exporter, release_8.0.2-119-g646f1a):

--8<---------------cut here---------------start------------->8---
#+OPTIONS: toc:nil author:nil

#+BEGIN_SRC sh :exports results :results output
cat testdiff.txt.orig
#+END_SRC

#+BEGIN_SRC sh :exports results :results output
diff testdiff.txt.orig testdiff.txt
#+END_SRC

#+BEGIN_SRC sh :exports results :results output
diff testdiff.txt.orig testdiff.txt | cat
#+END_SRC

#+BEGIN_SRC sh :exports results :results output
ls testdiff.*
#+END_SRC
--8<---------------cut here---------------end--------------->8---

                               __________

                                TESTDIFF
                               __________


,----
| asdf
| ghjk
`----

,----
| 1c1
| < asdf
| ---
| > qwer
`----

,----
| testdiff.html
| testdiff.org
| testdiff.txt
| testdiff.txt.orig
`----

Why is the `diff' command alone not exported while the piped `diff' via
`cat' works?  Is this this a bug?

-- 
Regards,
Oliver