Hey guys,

Try and do the following:

```bash
mkdir test && cd test
git init
flake8 --install-hook git
git config --bool flake8.strict true
echo a= 2 > foo.py && git add foo.py
git commit -m "This is bad!"
```

This commit is accepted! It shouldn't be.

Note that if you instead do

```bash
mkdir test2 && cd test2
git init
flake8 --install-hook git
git config --bool flake8.strict true
echo a= 2 > foo.py && git add foo.py
git commit -m "Add a foo file"
echo b =3 > foo.py && git add foo.py
git commit -m "This is bad!"
```

then the first commit is wrongly accepted, but the second commit (and any following) is correctly rejected.

My best guess: this has to do with `copy_indexed_files_to` in the line

```python
filepaths = list(copy_indexed_files_to(tempdir, lazy))
```

inside of the definition of `hook` from flake8.main.git

Curious to know your thoughts!

Cheers,
Mattia