[O] ob-octave.el raise error after execute src block

[stardiviner]

I got the following error after executing src block:

```

error: invalid call to script /usr/share/octave/4.2.2/m/help/ans.m

```

Here is my code:

#+begin_src octave :results file :dir "data/images" :file "figure1.png"
clf ();
surf (peaks);
saveas (1, "figure1.png");
#+end_src