Optional hook to prevent committing to master (#270)

Author: berquist

tools/hooks/README.md

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+# Git Hooks
+
+These are scripts executed by Git at specific steps of the version control workflow, depending on their name.
+
+- `pre-commit` runs before attempting to commit, and prevents committing to the local master branch.
+
+To install,
+```bash
+$ ./install_hooks.bash
+```
+
+To read more about hooks, read the [Pro Git chapter](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks).

tools/hooks/install_hooks.bash

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+#!/usr/bin/env bash
+
+set -o errexit
+
+# Grab the directory of _this_ script.
+SCRIPTDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+PROJECTDIR="$(realpath "${SCRIPTDIR}"/../..)"
+
+# Try to link each hook into the project's .git/hooks directory.
+for hook in $(ls "${SCRIPTDIR}"/*.hook); do
+    stub="${hook%.*}"
+    dest="${PROJECTDIR}/.git/hooks/$(basename ${stub})"
+    ln -sv "${hook}" "${dest}"
+done

tools/hooks/pre-commit.hook

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+#!/usr/bin/env sh
+
+# prevent commit to local master branch
+# taken from https://gist.github.com/aaronhoffman/ffbfd36928f9336be2436cffe39feaec#file-pre-commit
+
+branch=`git symbolic-ref HEAD`
+if [ "$branch" = "refs/heads/master" ]; then
+    echo "pre-commit hook: Cannot commit to the local master branch."
+    echo "Please make all your changes in a new feature branch:"
+    echo "$ git checkout -b my-new-feature-branch"
+    exit 1
+fi
+
+exit 0