git post-checkout hook that executes a "bundle install" if Gemfile has changes (using RVM if available)

post-checkout.sh

#!/bin/bash --login
orig_commit=$1
dest_commit=$2

root="$(git rev-parse --show-toplevel 2> /dev/null)"

is_not_rebasing() {
  test -d ${root}/.git/rebase-merge
}

is_gemfile_clean() {
  git --no-pager diff --exit-code --name-only ${orig_commit} ${dest_commit} \
    Gemfile Gemfile.lock > /dev/null
}

[[ -s .rvmrc ]] && . .rvmrc
is_not_rebasing && (is_gemfile_clean || bundle install)