Jujutsu unfriendly submit

[bolivier]

If you're using Jujutsu, you cannot submit despite the HEAD being on the correct commit (ie. the tip of the master branch). Jujutsu leaves you in a detached HEAD state by default. You can switch the branch manually, and then submit works as expected.

A slight change to the branch detection command (adds no dependencies, and still only relies on git) will allow Jujutsu users to seamlessly use the codecrafters CLI.

I'm happy to make the change myself, but I wanted to make sure it would be accepted.

The issue stems from this code:

cli/internal/commands/submit.go

Lines 104 to 111 in b460df3

	func getCurrentBranch(repoDir string) (string, error) {
	outputBytes, err := exec.Command("git", "-C", repoDir, "rev-parse", "--abbrev-ref", "HEAD").CombinedOutput()
	if err != nil {
	return "", wrapError(err, outputBytes, "get current branch")
	}
	return strings.TrimSpace(string(outputBytes)), nil
	}

This currently runs something like

git -C . rev-parse --abbrev-ref HEAD

and the following would make Jujutsu work as expected

git for-each-ref --format=%(refname:short) --points-at HEAD refs/heads

[rohitpaulk]

@bolivier the second command could (in theory) return multiple items - happy to accept a change for this if it's a bit more defensive (like only triggers when we know HEAD is detached or something similar?).