Usethis: Honor a default Git branch that is not `master`

[jennybc]

In the course of the git2r --> gert refactor, analyze how we can detect repo's default branch, i.e. don't assume or hard-wire it to master. Can probably be similar to how we figure out / respect user's preference for Git protocol (SSH vs HTTPS) or other usethis options.

Example of the mechanics of renaming master to main:

https://www.hanselman.com/blog/EasilyRenameYourGitDefaultBranchFromMasterToMain.aspx

[jennybc]

GitHub's advice and roadmap:

https://github.com/github/renaming

[jennybc]

Git project's statement:

https://sfconservancy.org/news/2020/jun/23/gitbranchname/

Code changes (unclear to me if this is a done deal or still just a proposal):

https://lore.kernel.org/git/[email protected]/

Most relevant excerpt for me:

There are now two config settings: init.defaultBranch (defining the branch name to use when initializing new repositories) and core.mainBranch (which is now configured by init_db(), declaring what the name of the main branch is in this repository).

[jennybc]

Because of the above, I think usethis should NOT implement its own solution but should fall in line with the above (e.g. the new git config settings), as it rolls out.

[jennybc]

Yet another set of instructions for changing default branch from master to something else. The advice here re: what other collaborators should do is the cleanest I've seen. Just want to save this link somewhere.

https://levelup.gitconnected.com/how-to-change-git-default-branch-from-master-3933afab08f9

[jennybc]

Best thread I've found yet on how to detect what the default branch on a remote is:

https://stackoverflow.com/questions/28666357/git-how-to-get-default-branch

You can dig this info out of the result of git remote show [your_remote].

But so far I see no way to achieve this with gert.

Update: discussed with @jeroen and we have the new gert::git_remote_ls()

[jeroen]

I've also updated an issue in libgit2: https://github.com/libgit2/libgit2/issues/5646

But for now, there is no reliable offline method, and you need gert::git_remote_ls() to see the default branch on the server.

[jennybc]

There's also an open PR on libgit2 to match Git's new support for init.defaultBranch:

https://github.com/libgit2/libgit2/pull/5581

This is a good thing to upvote. It is helpful for all of us if repos created by libgit2 "look" the same as those created with command line Git.