[bug][git-gui] Git gui is not executing prepare-commit-msg hooks when run from a worktree

Hello,

What did you do before the bug happened? (Steps to reproduce your issue)
- Create a worktree of a git in a new directory
- Add prepare-commit-msg hook
- Open `git gui` UI from the worktree directory

What did you expect to happen? (Expected behavior) It should fill the commit field with the hooks

What happened instead? (Actual behavior) Nothing

The hook works fine in the original directory (with the full .git)

[System Info] git version: git version 2.31.1 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Linux 5.4.0-77-generic #86-Ubuntu SMP Thu Jun 17 02:35:03 UTC 2021 x86_64 compiler info: gnuc: 9.3 libc info: glibc: 2.31 $SHELL (typically, interactive shell): /bin/bash

[Enabled Hooks] prepare-commit-msg