[babel] Bug when updating the hash: meta-lines get deleted

["Sebastien Vauban" <sva-news-D0wtAvR13HarG/iDocfnWg@public.gmane.org>]

Hello,

When results caching is enabled, and when the hash must be updated, the
"meta-lines" in front of the results block are _deleted_.

Such meta-lines include:
- ATTR_LaTeX lines
- BEGIN/END_CENTER environments

ECM:

--8<---------------cut here---------------start------------->8---
#+PROPERTY: cache yes

#+begin_src R
print("Hello")
#+end_src

#+ATTR_LaTeX: {\tiny
#+results[824ca019826a9f384bd35371065bb2418a1afedf]:
: Hello
#+ATTR_LaTeX: }
--8<---------------cut here---------------end--------------->8---

If you change the source code block (such a setting the string to
"Hello2"), you get the following Org buffer:

--8<---------------cut here---------------start------------->8---
#+PROPERTY: cache yes

#+begin_src R
print("Hello2")
#+end_src

#+results[663ebd0c20f3ed9105d254971336679e44354a3e]:
: Hello2

#+ATTR_LaTeX: }
--8<---------------cut here---------------end--------------->8---

Best regards,
  Seb

-- 
Sebastien Vauban