Fix TODO statistics bug

Fix TODO statistics bug

Alessandro Paccacio writes:

> I've an outline like this:
>
> * Project A
> ** TODO Task A-1 [0/3]
> *** TODO Subtask A-1-a
> *** TODO Subtask A-1-b
> *** TODO Subtask A-1-c
>
> where level 1 heading is the name of a project, level 2 heading is a
> generic task broken into three level 3 headings.  As suggested in
> section 5.5 of the manual, I've hooked the org-summary-todo function
> to org-after-todo-statistics-hook, in order to automatically change
> the level 2 TODO to DONE when all the subtasks are DONE.
> Unfortunately, when I change to DONE the first subtask, an unexpected
> TODO is added to level 1 heading:
>
> * TODO Project A
> ** TODO Task A-1 [1/3]
> *** DONE Subtask A-1-a
> *** TODO Subtask A-1-b
> *** TODO Subtask A-1-c
>
> From now on, the switch TODO->DONE or DONE/TODO applies to level 1
> heading, even if the [/] cookie in level 2 is correctly updated:
>
> * DONE Project A
> ** TODO Task A-1 [3/3]
> *** DONE Subtask A-1-a
> *** DONE Subtask A-1-b
> *** DONE Subtask A-1-c
>
> Is there a way to apply the automatic change of TODO to the parent
> heading only, as below?
>
> * Project A
> ** DONE Task A-1 [3/3]
> *** DONE Subtask A-1-a
> *** DONE Subtask A-1-b
> *** DONE Subtask A-1-c