This code does not work when init.defaultBranch is not set (see the failed CI builds for this PR).

In this case, you see the following:

$ irb
2.7.6 :001 > `git config --get init.defaultBranch`
 => "" 
2.7.6 :002 > $?
 => #<Process::Status: pid 54561 exit 1> 
2.7.6 :003 > 

I think you could get away with adding this line:

initial_branch = 'master' if initial_branch.empty?

See the docs for git init --initial-branch for more context.

yes, thanks for reminding me 🙏

I reproduced by removing defaultBranch = main in my ~/.gitconfig and changed the test case as your suggestion
I also did some commit cleanup(cherry-pick and force pushed)

also suggest rename test_git_init to test_git_init_with_default_init_default_branch