bug#58653: 29.0.50; Long lines in *compilation* buffer

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Date: Thu, 03 Nov 2022 07:11:18 +0100
> 
> Another observation: I have truncate-lines nil in *compilation*.  The
> continuation lines for the long gcc commands are displayed correctly
> with these "curly" arrows.  The lines showing errors or warnings that
> are chopped somehow display a triangle on the left margin, as if the
> line were scolled.  I can't make sense of that at all.

That "triangle" is likely the "overlay-arrow" as it is displayed on
GUI frames.