如何用python重写一个文件并得到一个合适的git diff？

import os
import subprocess

def rewrite_file(file_path, new_content):
    with open(file_path, 'w') as file:
        file.write(new_content)

file_path = 'path/to/file'  # 文件路径
new_content = 'new content'  # 新的文件内容
rewrite_file(file_path, new_content)

def get_git_diff(file_path):
    diff_output = subprocess.check_output(['git', 'diff', file_path])
    return diff_output.decode('utf-8')

file_path = 'path/to/file'  # 文件路径
git_diff = get_git_diff(file_path)
print(git_diff)