Error when handling non-ascii filename

[lubomir]

Steps to reproduce:

$ mkdir foo
$ cd foo
$ git init
$ touch 'bokm'$'\345''l.alias'
$ python -c 'import git; git.Repo(".").untracked_files'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.11/site-packages/git/repo/base.py", line 839, in untracked_files
    return self._get_untracked_files()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/git/repo/base.py", line 856, in _get_untracked_files
    filename = filename.encode("ascii").decode("unicode_escape").encode("latin1").decode(defenc)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe5 in position 4: invalid continuation byte

I can reproduce with 3.1.30 and 3.1.32.

A file with such name is present in ftp://ftp.gnu.org/gnu/aspell/dict/nb/aspell-nb-0.50.1-0.tar.bz2
I'm not sure what encoding it's supposed to be. Firefox detects it as windows-1252 (and displays it correctly).

[Byron]

The handling of filepaths is completely broken in GitPython as it tries to handle it like it's strings even though these imply a known encoding.

This could definitely use an overhaul, these issues are in many places.