Add git hook for package comparison

When moving to commit, this hook will automatically fire and check the
current system's installed packages against those explicitly committed
to the repository. If they mismatch it will inform the user.

It will not prevent the commit, but simply add a comment at the top of
the commit messages to remind the user that something is unbalanced
between both. It would be recommended to either check the additional
package into source control, remove it from the current system, or
explicitly add it to ignored packages.

install.sh

@@ -44,6 +44,19 @@ check_consent() {
   fi
 }
 
+enable_git_hooks() {
+  if [ "$1" == "false" ]; then
+    echo "Should we enable git hooks for this repository, so that installed packages are automatically compared when committing? [Y/n]"
+    read -r no
+    if [[ "$no" == n* ]]; then
+      echo "Not changing repository settings."
+      return
+    fi
+  fi
+  git config --local core.hooksPath .githooks/
+  echo "Changed repository settings."
+}
+
 install() {
   unattended=$1
   if ! "$unattended"; then
@@ -68,6 +81,9 @@ install() {
   # -- for some reason stow only works with unqoted var expansion
   stow -R ${targets} 2> >(grep -v 'Absolute/relative mismatch between Stow dir' 1>&2)
 
+  echo "================== ENABLING GIT REPOSITORY HOOKS =========================="
+  enable_git_hooks "$unattended"
+
   echo "====================== INSTALLATION FINISHED =============================="
   exit 0
 }