Hi all,
It looks like when I originally set up appveyor for yt a few years ago I did it incorrectly under my own github account instead of under the yt-project organization.
There are instructions for how to sign up for an organization account on appveyor here:
Someone (not me, I'm not sure which e-mail to use) will need to follow those instructions to set up a yt-project account on appveyor using an e-mail address controlled by the project or a project maintainer. Once that is set up you'll be able to update the webhook on the yt-project org to point at the new test setup on the yt-project appveyor account.
Sorry for setting this up in a bad way and sorry for any confusion this has caused, I honestly didn't realize until now that this was an issue.
-Nathan