bug#45915: 28.0.90; deletechar distorts org-table

[Tak Kunihiro <homeros.misasa@gmail.com>]

I confirm that there still is the problem with org-table on Emacs
28.0.90 pretest with org-version 9.5.1.

Here is a recipe to reproduce the problem.  I still have to stick to
26.3.

 1. emacs -Q
 2. (defun emacs-bug-reproduce-45915 () ...)
 3. (call-interactively 'emacs-bug-reproduce-45915)

(defun emacs-bug-reproduce-45915 ()
  "Reproduce bug#45915."
  ;; (gnus-read-ephemeral-emacs-bug-group 45915)
  (interactive)
  (with-current-buffer (get-buffer-create "*temp buffer*")
    (erase-buffer)
    (require 'org)
    (orgtbl-mode 1)
    (insert (format "emacs-version: %s, org-version: %s\n" emacs-version org-version))
    (insert "|   | rownames |
| / | <l>      |
|---+----------|
|   | a        |"))
  (switch-to-buffer-other-window "*temp buffer*")
  (execute-kbd-macro (kbd "M-< C-n C-n C-n C-n C-f C-f"))
  (message "I will hit S-<return>.")
  (sit-for 2)
  (execute-kbd-macro (kbd "S-<return>"))
  (message "I will hit <delete>.")
  (sit-for 2)
  (execute-kbd-macro (kbd "<delete>"))
  (message "I will call previous-line.")
  (sit-for 2)
  (call-interactively 'previous-line))

> I confirm that there is still problem with org-table
> on Emacs 29.0.50 with org-version 9.5.
>
>>>> I confirm that there still is following problem on 27.1.91.
>>>> Could someone take a look and show me work around?
>>> 
>>> I cannot reproduce this with latest Org stable version 9.4.5.
>>> 
>>> Can you try again and report?
>>
>> I downloaded Org 9.4.5 and reproduced the problem on 26.3, 27.2,
>> and 28.0.50. Here is a recipe again.
>>
>>> On certain condition, typing <deletechar> distorts alignment of
>>> a table.  Then, typing <up> moves point to previous line but far
>>> right position (column 14 instead of column 2).
>>> 
>>> |   | rownames |     |   | rownames |
>>> | / | <l>      |     | / | <l>      |
>>> |---+----------| ->  |---+----------|
>>> | / | a        |     |  | a        |
>>> 
>>> Here is a recipe to reproduce the glitch started from emcas -Q. 
>>> 
>>> 1. Create a buffer with (text-mode) and yank following table.
>>> 
>>> |   | rownames |
>>> | / | <l>      |
>>> |---+----------|
>>> |   | a        |
>>> 
>>> 2. (progn (require 'org) (call-interactively 'orgtbl-mode))
>>> 3. Move point to the first column and the third line with letter 'a'.
>>> 4. Hit <S-return>.
>>> 5. Hit <deletechar>.
>>> 6. Hit <up>.