Hi! A few reasons it might fail:
* You don't have your SSH keys on GitHub
* You don't have your GitHub keys on that laptop
* Your key is not RSA (because I'm LAZY)
* Your ssh version uses only recent algorithms not supported by Go's x/crypto/ssh
* You actually disabled IdentityKeys
Nothing to do with usernames or heuristics, by the way. All it does is first enumerate your client keys, then let you in, then check a huge GitHub keys database, then ask the GitHub API for your name.