How to set default branch for GitPython

Question

With GitPython, I can create a new repo with the following:

from git.repo.base import Repo

Repo.init('/tmp/some-repo/')

The repo is created with the default branch master.

How can I modify this default branch?

Update: As suggested in the answers below, I have tried using Repo.init('/tmp/some-repo', initial_branch="main"), however it renders this exception:

Traceback (most recent call last):
  File "/app/checker/tests.py", line 280, in test_alternative_compare_branch
    comp_repo_main = Repo.init(
  File "/usr/local/lib/python3.9/site-packages/git/repo/base.py", line 937, in init
    git.init(**kwargs)
  File "/usr/local/lib/python3.9/site-packages/git/cmd.py", line 542, in <lambda>
    return lambda *args, **kwargs: self._call_process(name, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/git/cmd.py", line 1005, in _call_process
    return self.execute(call, **exec_kwargs)
  File "/usr/local/lib/python3.9/site-packages/git/cmd.py", line 822, in execute
    raise GitCommandError(command, status, stderr_value, stdout_value)
git.exc.GitCommandError: Cmd('git') failed due to: exit code(129)
  cmdline: git init --initial-branch=main
  stderr: 'error: unknown option `initial-branch=main'

In the git docs, it states that the command for setting initial branch is --initial-branch (https://git-scm.com/docs/git-init/2.28.0#Documentation/git-init.txt---initial-branchltbranch-namegt).

Judging by the error, I think that the additional kwargs feature of GitPython is not including the -- prefix.

Meredeth

what is in repo? did you clone it, or is it an existing local directory? What's the purpose of this - do you want to skip cloning some objects or just want to find a way to checkout an existing branch using gitpython? – Territorialize

Hi @Marat, the repo is a new repo I have initialised using. I made a typo in the code above... I've corrected it now. – Meredeth

Answer 1

According to the docs, init takes the same arguments as git init as keyword arguments. You do have to turn - into _.

from git import Repo

Repo.init('/tmp/some-repo/', initial_branch='main')

---

UPDATE

initial-branch was added very recently in v2.28.0. You'll need to upgrade Git to use it.

If you can't, manually change the branch name with branch.rename(new_name). Unfortunately you can't do this until after the first commit, no branches truly exist yet. That's a Git limitation and why they added initial-branch and also the init.defaultBranch config option.

Hexosan

Yes I did see that but when I try your example it throws an error: stderr: 'error: unknown option initial-branch=main'... I need the two -- prefix but I can't figure out how to set it. – Meredeth

@Meredeth It's initial_branch. Note the underscore. You do not need the --. – Hexosan

Hey @Schwern, yes I tried that, but it didn't work. I edited the post with the details. Thanks for responding though! – Meredeth

@Meredeth That shows it's running git init --initial-branch=main which is correct. Check what version of Git GitPython is using. from git import Git, g = Git() and g.version_info. – Hexosan