Add script to fetch pull request

Author: RishabhJain2018

scripts/tools/fetch_pull_request

@@ -0,0 +1,13 @@
+#!/bin/bash
+if [ "$1" == "--help" ]; then
+    printf "Usage: fetch-pull-request [--help] pull_request_id [remote=origin] \n\n Locally fetch a pull request and test it. \n Remote is set to origin by default.\n"
+    exit 1
+elif [ $# -eq 0 ]; then
+    echo "Pull request id not given."
+    exit 1
+else
+    set -e -x
+    remote=${2:-origin}
+    git branch -D review-$1 || git fetch $remote pull/$1/head:review-$1
+    git checkout review-$1
+fi