When a user configures core.hooksPath = ~/gitconfig/hooks in .gitconfig,
_hooks_dir() was constructing Path("~/gitconfig/hooks") without calling
expanduser(), so hooks were installed into <repo>/~/gitconfig/hooks instead
of the intended absolute path.
Add Path.expanduser() call immediately after reading the raw string from
git config, before the is_absolute() / root-relative fallback logic.
Fixes#547
Koushik-Salammagari
e1947826fc