x/pkgsite: support viewing a package @ default branch HEAD

[hugelgupf]

Previously, #36811 added support for viewing packages at master on pkg.go.dev. Many repos are moving their default branch names away from master to main or something-else-not-master.

It seems that master is hard-coded in pkgsite.

Would it be possible to support some kind of magic version string that gets the default branch, whatever it may be named? This may end up being the reason that I move some of my repos back to master, which I'd like to avoid.

See also this comment as FYI

cc @julieqiu

[julieqiu]

Thanks @hugelgupf for bringing this up! We would like to add support for this, but can't get to it right now.

If someone wants to propose a design and send us a CL, we would be happy to accept the contribution!

[hajimehoshi]

Now specifying a default branch like @master takes the snapshot at that time, which is never updated. (e.g., https://pkg.go.dev/github.com/hajimehoshi/ebiten/v2@master) I'd be happy if we could update this.

[deadprogram]

Is anyone working on this at the moment? If so, please let yourself be known in this issue so we can hopefully coordinate efforts.

We moved to non-master branch for many repos, and also have changed all our links to point to pkg.go.dev for docs. I suspect that there are many of us in this situation at the moment, so it seems like a little bit of a collective priority.

[phouse512]

I am just coming across this issue as well. I have some time over the next few weeks to work on an approach if no one else has started. All of our repos are no longer using the master branch as default and we need a reliable way to publish.