Spotify stopped scrobbling to libre.fm - unable to login

I've set Spotify up to scrobble to libre.fm using the hosts file hack, as specified on the wiki, adding these two entries to my hosts file.

149.20.54.250 post.audioscrobbler.com
149.20.54.250 ws.audioscrobbler.com

This worked for a while. However, Spotify now tells me that it can't log in to libre.fm. I've double checked my username and password. I haven't changed anything else. Using nslookup confirms that the above names resolve to the correct IPs. So, how do I fix this?

I ran a wireshark capture and found that the server post.audioscrobbler.com was not responding properly. Navigating to that page showed me this:

It works!

This is the default web page for this server.

The web server software is running but no content has been added, yet.

Which seemed odd, as I recalled the libre.fm server actually serving something. I did some looking around the libre.fm website and it turns out that they have a new scrobbling server, but never updated the wiki. The correct server is turtle.libre.fm, and the hosts entry is

213.138.110.197 post.audioscrobbler.com

Oddly, there's a link from turtle.libre.fm to the wiki with the bad data.

It took me the better part of an afternoon to figure out this particular loop of bad documentation, so hopefully my answer here will save someone else a bit of searching.