Always reset user whois state upon 318

Based on this client to server interaction:

```
<< WHOIS test test
>> :server 263 test WHOIS :This command could not be completed because it has been used recently, and is rate-limited.
>> :server 318 test test :End of /WHOIS list.
```

the user is stuck with `@in_whois` raised and will never ever update whois.