[O] [Bug] element cache problem with repeating timestamps

[Matt Lundin]

A recent git pull broke logging with repeating todos. 

I'm guessing this has something to do with one of the recent changes to
the org element cache, since setting org-element-use-cache to nil solves
the problem.

Recipe to replicate:

1. /usr/bin/emacs -Q -l ~/minimal.el

Here is minimal.el:

minimal.el
Description: application/emacs-lisp

2. Open a file containing the following:

--8<---------------cut here---------------start------------->8---

* TODO Repeating task
  SCHEDULED: <2014-06-23 Mon 20:00 .+1d> 
  :LOGBOOK:
  - State "DONE"       from "TODO"       [2014-06-22 Sun 23:01]
  :END:
  :PROPERTIES:
  :LAST_REPEAT: [2014-06-22 Sun 23:01]
  :END:
--8<---------------cut here---------------end--------------->8---

3. Hit org-todo on the headline. The buffer then looks like this:

--8<---------------cut here---------------start------------->8---
* TODO Repeating task
<2014-06-23 Mon 20:00 .+1d>  SCHEDULED:  
  :LOGBOOK:
  - State "DONE"       from "TODO"       [2014-06-22 Sun 23:10]
  - State "DONE"       from "TODO"       [2014-06-22 Sun 23:10]
  - State "DONE"       from "TODO"       [2014-06-22 Sun 23:01]
  :END:
  :PROPERTIES:
  :LAST_REPEAT: [2014-06-22 Sun 23:10]
  :END:
--8<---------------cut here---------------end--------------->8---

Sometimes (more difficult to replicate) the LAST_REPEAT ends up in the
wrong place (e.g., the beginning of the buffer). Also, emacs sometimes
freezes when calling org-todo.

 - Org-mode version beta_8.3 (beta_8.3-16-g8ad206 @
   /home/user134/org-mode/lisp/)
 - GNU Emacs 24.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.12.2) of
   2014-06-11 on var-lib-archbuild-staging-x86_64-jgc

Thanks,
Matt