bug#63790: 30.0.50; prog-fill-reindent-defun regression

[Juri Linkov <juri@linkov.net>]

This regression is in master, not in emacs-29.

0. emacs-30 -Q
1. add to the beginning of the *scratch* buffer a list, so that
*scratch* looks like this:

(+
 1
    2
 3)

;; This buffer is for text that is not saved, and for Lisp evaluation.
;; To create a file, visit it with C-x C-f and enter text in its buffer.

2. Activate the region with the beginning at the start of the line with
the first comment, and the region end with point at the end of the buffer.

3. Type 'M-q' (prog-fill-reindent-defun)

It indents the list instead of the comment.

But when point is at the region beginning then 'M-q' correctly indents
the comments.