Bug: org-sort-entries does not preserve folded drawers [9.1.13 (9.1.13-dist @ /home/yantar92/.emacs.d/straight/build/org/)]

[Ihor Radchenko <yantar92@gmail.com>]

org-sort-entries seems to unfold everything in the subtree even if no
modification was done to the buffer during sorting.

Steps to reproduce:

Consider the following org file:
#+begin_src org
,* a
:PROPERTIES:
:ID:       279e797c-f4a7-47bb-80f6-e72ac6f3ec55
:END:
:DRAWER:
Blah
:END:
      
,** test
#+end_src

1. emacs -Q
2. Fold all the drawers and entries in the buffer
3a. Call M-x org-sort-entries p
3b. Call M-: (org-sort-entries nil ?p) RET


Expected behaviour for 3a: Subtree is unfolded, all the property drawers
are folded, buffer is unchanged
Observed behaviour for 3a: Subtree is unfolded, all the property drawers
are also unfolded, buffer is marked modified

Expected behaviour for 3b: Subtree is folded, all the property drawers
are folded, buffer is unchanged
Observed behaviour for 3b: Subtree is unfolded, all the property drawers
are also unfolded, buffer is marked modified

Regards,
Ihor




Emacs  : GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit)
 of 2019-04-29
Package: Org mode version 9.1.13 (9.1.13-dist @ /home/yantar92/.emacs.d/straight/build/org/)
-- 
Ihor Radchenko,
PhD,
Center for Advancing Materials Performance from the Nanoscale (CAMP-nano)
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Email: yantar92@gmail.com, ihor_radchenko@alumni.sutd.edu.sg