Add helper script for tagging a nightly build

This script will tag a Jenkins nightly build, using the name of the current
branch and the timestamp defined in the $datestamp variable or given
on the command line.

It should be used as a generic part of any production nightly Jenkins
build of athena.

Build/AtlasBuildScripts/tag_build.sh

+#! /bin/bash
+#
+# Copyright (C) 2017 CERN for the benefit of the ATLAS collaboration
+#
+
+# Function printing the usage information for the script
+usage() {
+    echo "Usage: tag_build.sh [-d date_stamp] [-u repository_url]" \
+		" Tag a 'nightly' build based on the current branch and timestamp."\
+		" This script should really only be used by NICOS to tag nightly builds."\
+		" Private builds should not do this."\
+        " 'date_stamp' defaults to $datestamp, repository_url to the ATLAS athena"\
+        " repository in CERN GitLab (krb5 authenticated)"
+}
+
+# Parse the command line arguments:
+DATESTAMP="$datestamp"
+REPOURL="https://:@gitlab.cern.ch:8443/atlas/athena.git"
+while getopts ":d:u:h" opt; do
+    case $opt in
+        d)
+            DATESTAMP=$OPTARG
+            ;;
+        u)
+            REPOURL=$OPTARG
+            ;;
+        h)
+        	usage
+        	exit 0
+        	;;
+        :)
+            echo "Argument -$OPTARG requires a parameter!"
+            usage
+            exit 1
+            ;;
+        ?)
+            echo "Unknown argument: -$OPTARG"
+            usage
+            exit 1
+            ;;
+    esac
+done
+
+# Check we got a datestamp and that it's a valid format
+if [ "$DATESTAMP" = "" ]; then
+	echo "No date_stamp defined from NICOS or given as a parameter"
+	exit 1
+fi
+echo $DATESTAMP | egrep "^[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{4}$" >& /dev/null
+if [ $? != "0" ]; then
+	echo "Datestamp '$DATESTAMP' does not correspond to the ATLAS format YYYY-MM-DDTHHMM"
+	exit 1
+fi
+
+# Abort if any of the next commands fail
+set -e
+
+# Use the source of this script to ensure that we cd to within the root of the
+# local repository
+ScriptSrcDir=$(dirname ${BASH_SOURCE[0]})
+cd $ScriptSrcDir/../..
+
+# Get branch name, then tag and push
+BRANCH=$(git symbolic-ref --short HEAD)
+TAG="nightly/$BRANCH/$DATESTAMP"
+echo "Creating tag $TAG"
+git tag $TAG
+git push $REPOURL $TAG