bug#38828: 26.3; Customized mode line breaks height of vertical scroll bar

[Eli Zaretskii]

> Cc: 38828@debbugs.gnu.org
> From: martin rudalics <rudalics@gmx.at>
> Date: Fri, 3 Jan 2020 16:57:12 +0100
> 
> It crashes thusly:
> 
>    CC       lastfile.o
>    CCLD     temacs.exe
> /usr/bin/mkdir -p ../etc
> make -C ../lisp update-subdirs
> make[2]: Verzeichnis „/c/emacs/trunk/non-32/lisp“ wird betreten
> make[2]: Verzeichnis „/c/emacs/trunk/non-32/lisp“ wird verlassen
> cp -f temacs.exe bootstrap-emacs.exe
> rm -f bootstrap-emacs.pdmp
> ./temacs --batch  -l loadup --temacs=pbootstrap
> make[1]: *** [Makefile:817: bootstrap-emacs.pdmp] Fehler 255

If you run the crashing command under GDB, what does it show at the
point of the crash?