While I'm a little annoyed by this (it seemed unlikely to me that GitHub would shut it down, so I actually used it), I can live with it. The "was only lightly documented" comment is pretty unnecessary and just adds insult to injury though. What's that supposed to mean? It feels like such an "it's kinda your fault for putting too much faith in us" insinuation. GitHub literally blogged about the feature [1], did they expect people not to use it because it wasn't "heavily" documented? Should their users ignore their blogs from now on, because apparently it's an irresponsible thing to take their blogs at face value?

Oh, and I don't think they've sent anyone any notifications about this, like the repo owners. Not sure how people are supposed to find out; are all users expected to stay up to date with GitHub's blog... which GitHub is telling them not to trust?

[1] https://github.blog/2011-11-10-git-io-github-url-shortener/