Reproducer for weird Emacs bug

Dockerfile

FROM docker.io/debian:unstable-20230208@sha256:b2f6fc00701e0d5ee6ef994891a6b4695865b51292fa2fb7a34882c15c7e4b4f
RUN apt-get update
RUN apt-get install -y emacs tmux
COPY repro.sh /
CMD /repro.sh

repro.sh

#!/bin/bash
set -xeEuo pipefail

emacs --version

rm -rf bug
mkdir bug
cd bug

# Ensure Emacs and tmux run in our little sandbox and don't interfere with the system
export HOME=$PWD
export TMUX_TMPDIR=$PWD
export XDG_RUNTIME_DIR=$PWD

# Create init files which cause the bug
mkdir .emacs.d
cat <<'EOF' > .emacs.d/init.el
(require 'bytecomp)
(byte-compile-file ".emacs.d/localvars.el")
(define-minor-mode dummy-mode "")
(defun turn-on-dummy-mode () (dummy-mode))
(define-globalized-minor-mode global-dummy-mode
  dummy-mode turn-on-dummy-mode)
(global-dummy-mode)
EOF
cat <<'EOF' > .emacs.d/localvars.el
;; Local Variables:
;; checkdoc-symbol-words: ()
;; End:
EOF

emacs --daemon

# Start ten emacsclients (use tmux to allow them to run concurrently)
for n in $(seq 10) ; do
	tmux new-session -d -s emacsbug-$n 'emacsclient -nw'
done

sleep 1

# Kill all emacsclients simultaneously
tmux kill-server

sleep 1

# Test that the bug occurs. One symptom is that the scratch buffer is cleared.
# This prints 1 if the bug occurs and 146 if the bug did not occur.
emacsclient  --eval '(with-current-buffer (get-buffer "*scratch*") (point-max))'