EAGLESIX-2653: Add tag cloning to shallowClone

lib/pipeline/matcher/ExistsMatchExpression.js

@@ -71,6 +71,8 @@ proto.matchesSingleElement = function matchesSingleElement(e) {
 proto.shallowClone = function shallowClone(){
 	var e = new ExistsMatchExpression();
 	e.init(this.path());
+	if (this.getTag())
+		e.setTag(this.getTag().clone());
 	return e;
 };