binderhub: New repos on Github no longer work by default with MyBinder

https://github.com/coiled/dask-mini-tutorial/ leads to a 404 page. Is it a private repo? If you need more help please use https://discourse.jupyter.org/

@manics I thought it wasn’t but I just realized it is. I’m so sorry, I apologized for the inconvenience.

So in my world, a hacky route would go from:

        if ref is None:
            await self.fail("Could not resolve ref for %s. Double check your URL." % key)
            return

to:

        if ref is None:
            fail_message = ["Could not resolve ref for %s." % key]
            unresolved_branch = key.split("/")[-1]
            if unresolved_branch == "master":
                 fail_message.append( 'Github recently changed default branches from "master" to "main". Did you mean the "main" branch?')
            elif unresolved_branch == "main":
                 fail_message.append('Github recently changed default branches from "master" to "main". Did you mean an original "master" branch?')
            fail_message.append("Double check your URL.")
            await self.fail(" ".join(fail_message))
            return

but you probably want something cleaner than that…

But as I say, I’m not really in a position to test it…

Hey @psychemedia! 👋 We were just discussing this in Gitter!

I can devote some time to addressing this next week

TODOs:

• Update hard-coded reference to master to be main. PR https://github.com/jupyterhub/binderhub/pull/1172
• Update error message here. Adding an extra check for if unresolved_ref == 'master' or ‘main’ and expanding the message in those two cases (main == likely user used default and repo uses master; master == likely old link, repo has been updated to use main) PR https://github.com/jupyterhub/binderhub/pull/1170
• Add a notice box to the mybinder.org homepage template notifying users of the change. Homepage template