bug#42039: 27.0.91; (posn-x-y (posn-at-point)) inconsistent with display-line-numbers-mode

[Eli Zaretskii]

> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Thu, 25 Jun 2020 16:29:21 +0300
> 
> 1. Enable display-line-numbers-mode.
> 2. Move point to the beginning of some line.
> 3. Evaluate (posn-x-y (posn-at-point))
> 
> => The value in CAR will be > 0 (to account for the columns taken by 
> d-l-n-m).
> 
> 4. Do the same thing on a line that belongs to an overlay. For example,
> the overlay in the bug reporting buffer (move point to the line with
> "This bug report...").
> 5. The return value will be like (0 . 180).

The bug-report buffer doesn't use an overlay, it uses a display
property string.  Do you have an example with an overlay where this
problem happens, or is it limited to display strings?