Source mirror no longer has rsync?

Whenever my mirrors try to sync, they get:

```
rsync: did not see server greeting
rsync error: error starting client-server protocol (code 5) at main.c(1850) [Receiver=3.4.1]
```

This is when using `rsync://mirrors.tuna.tsinghua.edu.cn/arch4edu/` as source URL, as specified in the wiki.