Overlay behavior change

[Gregory Heytings]

Hi,

Since at least Emacs 21, overlays between two buffer positions, when these 
two positions are on different lines, extend to the right border of the 
window.  In Emacs 28.0.50 this is not the case anymore, overlays extend 
only one character position after the last character of the line.  Sample 
code (put the cursor on, say, 'lambda' and press C-t):

(global-set-key
 (kbd "C-t")
 (function
   (lambda ()
     (interactive)
     (let* ((start (point))
            (end (progn (save-excursion (forward-line 5) (point))))
            (o (make-overlay start end)))
    (overlay-put o 'face '(:background "green"))))))

Is this change intentional?  It does not seem to be documented in the 
NEWS, and I did not find it in the ChangeLogs either (but perhaps I did 
not look carefully enough).  How can one get the previous default 
behavior?

Gregory