pkgs/git-checkout-github-pr: Add script to checkout GitHub PRs in repos

pkgs/git-checkout-github-pr/git-checkout-github-pr.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+ID=""
+REMOTE="origin"
+LOCAL_BRANCH=""
+
+while [[ $# -gt 0 ]]; do
+	case $1 in
+		--remote)
+			REMOTE="$2"
+			shift
+			shift
+		;;
+		--local-branch)
+			LOCAL_BRANCH="$2"
+			shift
+			shift
+		;;
+		*)
+			if [[ -z "${ID}" ]]; then
+				ID="$1"
+				shift
+			else
+				echo "Unknown option $1"
+				exit 1
+			fi
+		;;
+	esac
+done
+
+if [[ -z "${ID}" ]]; then
+	echo "Specify GitHub PR number"
+	exit 1
+fi
+
+if [[ -z "${LOCAL_BRANCH}" ]]; then
+	LOCAL_BRANCH="pr/${ID}"
+fi
+
+git fetch "${REMOTE}" "pull/${ID}/head:${LOCAL_BRANCH}"
+
+git switch "${LOCAL_BRANCH}"