repro.sh

#!/usr/bin/env bash
set -euo pipefail

ROOT="/home/hacnho/Projects/huntr-mfv/laneB-4k-formats"
VENV="$ROOT/.venv-msgpack-121/bin/python"

echo "[1] latest msgpack"
"$VENV" - <<'PY'
import importlib.metadata as m
print(m.version("msgpack"))
PY

echo "[2] real parser path"
"$VENV" - <<'PY'
import msgpack
data = open("/home/hacnho/Projects/huntr-mfv/laneB-4k-formats/messagepack-nested-5000.msgpack", "rb").read()
msgpack.unpackb(data, raw=False)
PY