[Bug] isearch errors when org-fold-core-style is 'overlays

[Matt Lundin <mdl@imapmail.org>]

I'm finding that isearch fails to unfold the correct region or to search
in the correct region when there are folded regions in a buffer and
`org-fold-core-style` is set to 'overlays.

Here is a minimal recipe for reproducing the bug:

Use a minimal emacs startup file:

--8<---------------cut here---------------start------------->8---
(add-to-list 'load-path "~/org-mode/lisp/")
(setq org-startup-folded t)
(setq org-fold-core-style 'overlays)
--8<---------------cut here---------------end--------------->8---

Open the following file:

--8<---------------cut here---------------start------------->8---
* One
word
* Two
word
--8<---------------cut here---------------end--------------->8---

Issue #1:

Go to the beginning of headline "Two" when the trees are folded.

Type "M-x isearch word [RET]".

Expected behavior: isearch should reveal the entry under headline two
and shift the highlighted region dynamically as the characters typed
begin to match.

What happens: the beginning of the highlighted region remains stuck at
the beginning of the headline and the entry does not unfold until after
the return key is pressed.

Issue #2:

Cycle headlines to folded state. Go to the beginning of headline "Two".

Type "M-x isearch word [RET]".

Note that during this second search dynamically highlighted region
expands to include the folded headline "One". Once return is pressed,
isearch reveals the entry under headline "One" and moves the point to
the "word" there. 

After running git bisect, I traced the issue to commit
6cd7c6fb1cf6363f1057086760bed9875cdd97c7

Thanks,

Matt