Bug or expected behavior? org-sparse-tree visibility toggling

[Cassio Koshikumo <ckoshikumo@gmail.com>]

I don't know if this can be considered a bug or if I'm trying to do
something not supported.

Create an .org file with the following contents:

* First Level
** One :tag:
*** Child
** Two
** Three
** Four :tag:
** Five

Now, C-c / m (or M-x org-sparse-tree and select m) and Match: tag.

The resulting sparse tree looks like this:

* First Level
** One :tag:
*** Child
** Four :tag:

So far, so good. Now, put point on heading One and press TAB. Child is hidden.

The problem: press TAB again. Now Two and Three are also shown,
effectively breaking the sparse tree filtering. (Actually Five is
shown, too, it seems...)

As far as I can tell, this only happens when the heading has a
subheading, like Child. But even when dealing with headings that DON'T
have a subheading, the ellipsis kinda breaks and ends up in the next
line, and successive TABs do nothing.

(In fact, I was trying different variations of the tree just now and
it seems the behavior is WILDLY inconsistent. If there's a blank line
between One and Child, then the first TABalready messes the tree up.
Don't know if further variations produce other results.)

So, can these behaviors be considered bugs? Or are sparse trees not
meant to have their visibility manipulated like this, and should be
considered a static, filtered view of the tree, with interactions
discouraged?

Thanks!

-- 
Cassio Koshikumo