Overcommit forbids brew installation

[boardfish]

$ OVERCOMMIT_DISABLE=1 brew install focusaurus/homebrew-shfmt/shfmt
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
The pre-rebase hook refused to rebase.
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
The pre-rebase hook refused to rebase.
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
The pre-rebase hook refused to rebase.
Updating Homebrew...
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
The pre-rebase hook refused to rebase.
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
The pre-rebase hook refused to rebase.
==> Tapping focusaurus/shfmt
Cloning into '/usr/local/Homebrew/Library/Taps/focusaurus/homebrew-shfmt'...
remote: Counting objects: 5, done.
remote: Compressing objects: 100% (4/4), done.
remote: Total 5 (delta 0), reused 3 (delta 0), pack-reused 0
Unpacking objects: 100% (5/5), done.
This repository contains hooks installed by Overcommit, but the `overcommit` gem is not installed.
Install it with `gem install overcommit`.
Error: Failure while executing; `git clone https://github.com/focusaurus/homebrew-shfmt /usr/local/Homebrew/Library/Taps/focusaurus/homebrew-shfmt --depth=1` exited with 64.

I set the GIT_TEMPLATE_DIRECTORY to overcommit --template-dir as in the docs. When brew needs to clone a repository, it fails, likely due to Overcommit's interference.

[sds]

Hey @boardfish, thanks for the report. A likely easy fix is to install the Overcommit gem in whatever Ruby is executed when you run Homebrew.

The reason why we can't offer a solution is that specifying GIT_TEMPLATE_DIRECTORY literally copies files from a directory that is included with the gem. The error message you get is telling you that the Overcommit gem is not installed in whatever version of Ruby runs by default (so outside the context of a shell with rvm/rbenv correctly set up).

You'll need to figure out which Ruby version this is on your side and install Overcommit appropriately. My guess is that Homebrew clones the repos in an isolated environment so that the environment variable you specified on the command line doesn't pass through.

Hope that helps!