Pulls and pushes fail when diffed paths contains : because of a bug in gitpython

[langfield]

See gitpython-developers/GitPython#1490.

Stack trace below.

ERROR:git.cmd:Pumping 'stdout' of cmd(['git', 'diff-tree', 'a31de9c31a0ee03574a34146aa1a986648ac499b', '7a62039cb6ce50e5d4c8fc412fdaf10e6f92b823', '-r', '--abbrev=40', '--full-index', '-M', '--raw', '-z', '--no-color']) failed due to: ValueError("invalid literal for int() with base 10: 'n'")
Exception in thread Thread-12:
Traceback (most recent call last):
  File "/home/user/conda/envs/anki/lib/python3.9/site-packages/git/cmd.py", line 114, in pump_stream
    handler(line)
  File "/home/user/conda/envs/anki/lib/python3.9/site-packages/git/diff.py", line 570, in <lambda>
    handle_process_output(proc, lambda byt: cls._handle_diff_line(byt, repo, index),
  File "/home/user/conda/envs/anki/lib/python3.9/site-packages/git/diff.py", line 557, in _handle_diff_line
    diff = Diff(repo, a_path, b_path, a_blob_id, b_blob_id, old_mode, new_mode,
  File "/home/user/conda/envs/anki/lib/python3.9/site-packages/git/diff.py", line 303, in __init__
    self.a_mode = mode_str_to_int(a_mode) if a_mode else None
  File "/home/user/conda/envs/anki/lib/python3.9/site-packages/git/objects/util.py", line 80, in mode_str_to_int
    mode += int(char) << iteration * 3
ValueError: invalid literal for int() with base 10: 'n'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/user/conda/envs/anki/lib/python3.9/threading.py", line 973, in _bootstrap_inner
    self.run()
  File "/home/user/conda/envs/anki/lib/python3.9/threading.py", line 910, in run
    self._target(*self._args, **self._kwargs)
  File "/home/user/conda/envs/anki/lib/python3.9/site-packages/git/cmd.py", line 120, in pump_stream
    raise CommandError([f'<{name}-pump>'] + remove_password_if_present(cmdline), ex) from ex
git.exc.CommandError: Cmd('<stdout-pump>') failed due to: ValueError('invalid literal for int() with base 10: 'n'')
  cmdline: <stdout-pump> git diff-tree a31de9c31a0ee03574a34146aa1a986648ac499b 7a62039cb6ce50e5d4c8fc412fdaf10e6f92b823 -r --abbrev=40 --full-index -M --raw -z --no-color

A temporary fix is just installing from a fork with the patch.

[langfield]

Fixed by #94.