I first ran into this when discovering that --exclude-vcs-ignores would probably help out my backup scripts a whole lot, considering  each thing I build has gigabytes of build artefacts. Unfortunately, it didn't seem to work all the time. I eventually narrowed it down to the fact that Rust by default adds a `/target/` entry to .gitignore instead of just `target/`. The latter works fine, while the former is incorrectly recognised by GNU tar.

I think fixing this would just mean stripping leading slashes from .gitignore files whenever tar reads them.