GitHub is running extra copies, indexed by Google

Seems like it's just some misconfigured DNS. Any subdomain is showing the same thing:

Pretty sure it's just the package registry, goto https://rubygems.pkg.github.com/

and you get JSON back.

{ status: "ok", message: "Hello, world! This is the GitHub Package Registry." }

But this probably shouldn't be indexed this way.

Is GitHub not indexed by Google anyway? I'm probably out of the loop on something here.

I don’t get it. What is this showing?

Duplicates of entire GitHub site (reasons unknown), hosted by GitHub, publicly available and therefore indexed by Google Search, so it's showing up on search results.

They're probably not duplicate sites. I wonder if this is some weird config bug.

Use rel=canonical tags guys!

I wonder if they may be up when github.com is down