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

[Stefan Kangas]

found 74924 29.3
found 74924 31.0.50
tags 74924 + confirmed
thanks

Ture Pålsson <ture@turepalsson.se> writes:

> 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.
>
> My *guess* is that this is related to the changes in commit
> 7e387c9e5265b98dbb3b986f8ab8ac2217052831, but that may well be a red
> herring.

I can reproduce this on both 29.3 and master on GNU/Linux.