bug#52163: 28.0.60; visual-line-mode breaks C-a and C-e in extreme case

[Eli Zaretskii]

> Date: Sun, 28 Nov 2021 14:49:04 +0000
> From: iung--- via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> * Reproducing
> - Case 1:
>    emacs -Q
>    C-u 999 a
>    visual-line-mode
>    C-p C-a
>    C-e C-a

What are the problems you see in this recipe?  Please be specific,
because it could be that what you see on your system we cannot see on
ours.

Also, please show all the information about your build collected by
report-emacs-bug, it could be important while investigating this
issue.

> Increase or decrease text-scale to make this behaviour appear/

If you see problems when you change the text scale, it's because the
screen line's width isn't an integral multiple of the character width.
That's normal and isn't a bug (not one we'd like to fix, anyway).