[bug report] git diff --relative not doing well with worktree in hooks

Hello,

I noticed a weird behavior when using git diff --relative with worktrees and hooks. When called from a pre-commit hook from a worktree, the relative option has no effect.

Here is how to reproduce the issue:

```bash mkdir hook-repro && cd hook-repro git init test && cd test mkdir folder && touch folder/.gitkeep && git add folder git commit -m 'init' cat <<EOF > .git/hooks/pre-commit #!/bin/bash

cd folder || exit

pwd # display the current working directory

git diff --cached --relative --name-only EOF chmod +x .git/hooks/pre-commit ```

```bash echo "foo" > folder/bar git add folder git commit -m "test" ```

Displays ``` /home/arch/git/awfus/hook-repro/test/folder bar ```

Now creating a worktree:

```bash git worktree add ../worktree && cd ../worktree echo "bar" > folder/foo git add folder git commit -m "worktree" ```

Displays ``` /home/arch/git/awfus/hook-repro/worktree/folder folder/foo ```

The path is no longer show relative. This causes issues with more complex scripts.

Git version: 2.45.0 (x86_64) on Arch Linux, shell is zsh (bash for the hook script)

Let me know if you need any more information :)