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

[Daniel Clemente <n142857@gmail.com>]

> So maybe you could bisect your init files and find the
> customization(s) which make the reproduction possible?  Because I
> cannot reproduce any of this here, no matter what I try.

I'm trying to reproduce it again and again, and I can't find the way,
not even with my full .emacs. Yesterday it happened (I just posted
here BT1 and BT2) but today I can't, so I guess there are other
factors apart from GC and resizing.
I'll keep trying to use emacs normally and I guess then it should
happen when I least expect it.

For reference: I automated an automated continuous X window resizer:
EC=$(xdotool search --name '^\*E\* \.emacs') && echo $EC && while :;
do for height_px in `seq 275 -25 10`; do xdotool windowsize $EC
$((height_px+5)) $height_px; sleep 0.001; done;   for height_px in
`seq 1 25 400`; do xdotool windowsize $EC $((height_px+5)) $height_px;
sleep 0.1; done;     sleep 0.3 && done

And I keep trying to cause GC, with things like:
;; (cl-loop for i from 300000 downto 1 do (+ 2.00 (+ 2.0 (+ 2.0 (+ 2.0
(+ 2.0 2.0))))))
;; (cl-loop for j from 100 downto 1 do (progn (cl-loop for i from
30000 downto 1 do (+ 2.00 (+ 2.0 (+ 2.0 (+ 2.0 (+ 2.0 2.0))))))
(sit-for 1)))
;; (cl-loop for i from 3000000 downto 1 do (garbage-collect))

But this formula hasn't ever worked yet, so I guess I'm missing other factors.