Create a new branch like `git branch <branch_name> <start_point>`.

def git_branch(repo_dir, branch_name, start_point='HEAD',
               force=True, verbose=True, checkout=False):
    """Create a new branch like `git branch <branch_name> <start_point>`."""
    command = ['git', 'branch']
    if verbose:
        command.append('--verbose')
    if force:
        command.append('--force')
    command.extend([branch_name, start_point])
    branch_output = execute_git_command(command, repo_dir=repo_dir)
    if checkout:
        return git_checkout(repo_dir, branch_name)
    else:
        return branch_output