I could be wrong, but I don't believe there is "hardcoded[d] GitHub magic".
IIRC I have used GitLab and Bitbucket and self-hosted Gitea instances the same exact way, and I'm fairly sure there was an hg repo in one of those. Don't recall doing anything out of the ordinary compared to how I would use a github URL.
Ouch, Go never ceases to amaze. The Bitbucket case[0] is even more crazy, calling out to the Bitbucket API to figure out which VCS to use. It has a special case for private repositories, but seems to hard-code cloning over HTTPS.
If only we had some kind of universal way to identify resources, that told you how to access it...
Wow, that's sad. I'm glad it works seamlessly, don't get me wrong, but I was assuming I could chalk it up to defacto standards between the various vendors here.
IIRC I have used GitLab and Bitbucket and self-hosted Gitea instances the same exact way, and I'm fairly sure there was an hg repo in one of those. Don't recall doing anything out of the ordinary compared to how I would use a github URL.