bug#74924: 29.3; Buffer showing manpage jumps back to beginning

[Eli Zaretskii]

> From: Ture Pålsson <ture@turepalsson.se>
> Date: Tue, 17 Dec 2024 10:07:18 +0100
> 
> 
> 1. Run in a terminal window. Operating system seems not to matter; I can
> reproduce on both macOS and Linux.
> 
> 2. Set environment variable MANWIDTH to 80 .
> 
> 3. Start Emacs ('emacs -nw -Q').
> 
> 4. Do M-x man, enter the name of some manpage, and type RET.
> 
> 5. Switch to the manpage window (C-x o), and scroll down by typing 'C-v'
> a few times.
> 
> 6. Switch back to the *scratch* window (C-x o again).
> 
> 7. After about a second, the manpage window jumps back to the beginning
> of the buffer.

Does the async command ('man' and the filter into which 'man' is
piped) still run when you do the above?  Or is this after the
background formatting has ended?  I'm guessing the former.