Add 'setup-hooks' script to install local hooks

Fetch the hooks right out of the local clone if possible.  Otherwise
fall back to a project-configured remote repository.

setup-hooks

+#!/usr/bin/env bash
+#=============================================================================
+# Copyright 2010-2012 Kitware, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#=============================================================================
+
+# Run this script to set up local Git hooks for this project.
+
+# Project configuration instructions:
+#
+# - Publish a "hooks" branch in the project repository such that
+#   clones will have "refs/remotes/origin/hooks".
+#
+# - Populate adjacent "config" file with:
+#    hooks.url    = Repository URL publishing "hooks" branch
+#    hooks.branch = Repository branch instead of "hooks"
+
+egrep-q() {
+	egrep "$@" >/dev/null 2>/dev/null
+}
+
+die() {
+	echo 1>&2 "$@" ; exit 1
+}
+
+# Make sure we are inside the repository.
+cd "${BASH_SOURCE%/*}" &&
+
+# Select a hooks branch.
+if url=$(git config --get hooks.url); then
+	# Fetch hooks from locally configured repository.
+	branch=$(git config hooks.branch || echo hooks)
+elif git for-each-ref refs/remotes/origin/hooks 2>/dev/null |
+     egrep-q 'refs/remotes/origin/hooks$'; then
+	# Use hooks cloned from origin.
+	url=.. && branch=remotes/origin/hooks
+elif url=$(git config -f config --get hooks.url); then
+	# Fetch hooks from project-configured repository.
+	branch=$(git config -f config hooks.branch || echo hooks)
+else
+	die 'This project is not configured to install local hooks.'
+fi &&
+
+# Populate ".git/hooks".
+echo 'Setting up git hooks...' &&
+git_dir=$(git rev-parse --git-dir) &&
+cd "$git_dir/hooks" &&
+if ! test -e .git; then
+	git init -q || die 'Could not run git init for hooks.'
+fi &&
+git fetch -q "$url" "$branch" &&
+git reset -q --hard FETCH_HEAD || die 'Failed to install hooks'