import git

repo = git.Repo.init('test_git')
with open('test_git/f.txt', 'w') as f:
    f.write('aa')
with open('test_git/g.txt', 'w') as f:
    f.write('bb')
repo.index.add('f.txt')
repo.index.add('g.txt') # < fails here
repo.index.commit('initial commit')
repo.close()

(venv) PS C:\test> python .\test_git_close.py

Traceback (most recent call last):
  File ".\test_git_close.py", line 9, in <module>
    repo.index.add('g.txt')
  File "venv\lib\site-packages\git\index\base.py", line 823, in add
    self.write(ignore_extension_data=not write_extension_data)
  File "venv\lib\site-packages\git\index\base.py", line 221, in write
    lfd.commit()
  File "venv\lib\site-packages\gitdb\util.py", line 359, in commit
    self._end_writing(successful=True)
  File "venv\lib\site-packages\gitdb\util.py", line 384, in _end_writing
    remove(self._filepath)
  File "venv\lib\site-packages\gitdb\util.py", line 83, in remove
    return _retry(os.remove, *args, **kwargs)
  File "venv\lib\site-packages\gitdb\util.py", line 77, in _retry
    return func(*args, **kwargs)
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'test_git\\.git\\index'