[O] [BUG] org-toggle-time-stamp-overlays does not work in #+DATE line

[Matt Lundin]

Steps to replicate.

1. Evaluate the following:

(setq org-time-stamp-custom-formats '("<%B %e, %Y>" . "<%B %e, %Y>"))

2. Use the following sample org file. 

--8<---------------cut here---------------start------------->8---
#+DATE: [2014-07-30 Wed 22:05]

* Headline
  [2014-07-30 Wed 22:05]
--8<---------------cut here---------------end--------------->8---

3. M-x org-toggle-time-stamp-overlays

The buffer should look like this:

--8<---------------cut here---------------start------------->8---
#+DATE: [2014-07-30 Wed]

* Headline
  [2014-07-30 Wed]
--8<---------------cut here---------------end--------------->8---

4. M-x org-toggle-time-stamp-overlays

The buffer now looks like this:

--8<---------------cut here---------------start------------->8---
#+DATE: [2014-07-30 Wed 22:05]

* Headline
  [2014-07-30 Wed 22:05]
--8<---------------cut here---------------end--------------->8---

...thus preventing any easy editing of the timestamp in the #+DATE
line.

Best,
Matt