Upstream bugfixes.

[gabyx]

For your info, if this might be the case here too.

Failing a reference-transaction 'prepared- hook is really ugly and lead to problems...

gabyx/Githooks#70

[gabyx]

Here is another bugfix you might be interested:

gabyx/Githooks#84

When running the git hooks ... -> Try to unset GIT_DIR and probably GIT_WORKTREE (?)
because git sets this when accidentially inside a .git dir. Resorting to all sorts of stupid problems (executing install --global in your if I can remember etc...) .
Rather unset it because its not needed.