check-useless-excludes meta hook doesn't seem to work well with broken symlinks #2019

Repro steps

1. Add a submodule
2. Add a symlink to somewhere inside this submodule
3. Use check-symlinks
4. Deinit submodule (to simulate the case when people clone without --recursive)
5. Notice that it now complains about the symlink created on 2
6. Add an exclude entry with the path to that symlink
7. Use check-useless-excludes
8. Notice that it complains that the added exclude entry doesn't apply.

For a working example, check out https://github.com/pkoch/test-check-useless-excludes (without --recursive, or run git submodule deinit --all) and run pre-commit run --all.