Subject: 27.1; `display-line-numbers-mode`, line numbers hidden with multiline overlays

From: Daniel Mendler <[email-masked]>
Date: Mon, 19 Apr 2021 16:46:16 +0200

When putting an overlay over multiple lines, the line numbers of
`display-line-numbers-mode` are hidden.

(defun bug ()
   (display-line-numbers-mode)
   (goto-char (point-min))
   (let ((ov (make-overlay (line-beginning-position)
                           (save-excursion (forward-line 4)
                                           (line-beginning-position)))))
     (overlay-put ov 'invisible t)
     (overlay-put ov 'before-string "line1\nline2\nline3\line3\nline4\n")))

I've also observed the issue with Emacs 28.

In GNU Emacs 27.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.5, 
cairo version 1.16.0)
  of 2021-02-09, modified by Debian built on 3df710f593d9
Repository revision: b0229d4bbaea7fcddffced393512c650212830db
Repository branch: deb/emacs/d/sid/master
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux 10 (buster)