Riffing on this thread alongside Binderhub button - 'pull from referrer' (and maybe Binder template repositories) I wonder (feature creep ;-)…
Docs around @manics recent https://github.com/jupyterhub/binderhub/pull/891 PR suggests:
In a GitHub repo create a readme with a link to
https://binder.example.org/autodetect, if it works the referrer will be parsed and converted into a link to launch the repo you came from.
So what if there was also a redirect saying: “(and) by default/convention look for a “binder-base” branch in the same same directory; if it exists, build / pull that, and then top up with content from an nbgitpulled content repo”.
For example, running:
https://github.com/user/example as referrer;
https://github.com/user/example into the binder image
Complicating further, there may also be a need to allow users to over-ride the gitpulled branch name with an arbitrary one, as well as allowing Binder to autodetect a referral from a branch specifying content from that branch is the content to be pulled in?