Cloning with options single branch and ref = HEAD is broken for repo with main base branch

[jjalfaro9]

Hey y'all ✌️🤠!

Repositories are shifting over to using main as their base branch.
Today go-git does not work as expected when cloning a repo with main = head and the following options:

&git.CloneOptions{
 	URL:          url,
 	Depth:        1,
 	SingleBranch: true,
 	ReferenceName: plumbing.HEAD,
 }

I kind of dug around and noticed that go-git hardcodes to plumbing.Master.Short() here:

go-git/repository.go

Lines 905 to 908 in 4ec1753

	case o.SingleBranch && o.ReferenceName == plumbing.HEAD:
	return []config.RefSpec{
	config.RefSpec(fmt.Sprintf(refspecSingleBranchHEAD, o.RemoteName)),
	config.RefSpec(fmt.Sprintf(refspecSingleBranch, plumbing.Master.Short(), o.RemoteName)),

This is the git command equivalent:
git clone --single-branch --depth=1 {REPO_URL_WITH_MAIN_BRANCH_AS_BASE}
The expected behavior is that it clones the repository with HEAD pointing to main. go-git returns an error stating couldn't find remote ref "refs/heads/master".

Is this something that y'all are aware of or on y'all's road map?
I am more than happy to help contribute a fix!
Just would need some guidance & more time to figure out how config.RefSpec works and why it's hardcoded to plumbing.Master.Short() in the switch statement above.

[Ferada]

Bump, ran into this, I'm using a hardcoded refs/heads/main for git.PlainClone, but ideally(?) you'd not need to specify anything regardless of whether it's master or main, right?

[jjalfaro9]

That's correct! Remote head could also be something entirely different than master or main.
I think the git implementation goes through these steps to determine the remote head:
guess_remote_head:

1. if transport supports directly peeking where HEAD points to, use that
2. if the git_default_branch_name (from the git configuration: key init.defaultbranch) exists at remote, use it
3. finally, you fall back to the hard-coded historical default: master