OK. I get an access token. I verify it using curl -H "Authorization: OAuth <token>" --url https://id.twitch.tv/oauth2/validate. I get a successful response, so I know the access token is good. I then open telnet onto irc.twitch.tv at port 6667. I then send PASS oauth:token and then I send NICK mynicknameinalllowercase. I get a Login authentication failed. error.