bug#71289: 30.0.50; cmcheckmagic aborts when tty_write_glyphs writes "Garbage collecting..." in some cases

[Daniel Clemente]

> When you do "C-x 2", does Emacs divide the root window horizontally or
> vertically?  Are the windows one above the other or are they side by
> side?

One above the other.
It doesn't crash if I divide them left/right. I can even use the
auto-resizer loop and it doesn't crash, but as soon as I do C-x 2, it
crashes.