Merge pull request #492 from sco0ter/smDelay

Don't add multiple delayed delivery extension to resent messages.

src/java/org/jivesoftware/openfire/streammanagement/StreamManager.java

@@ -178,10 +178,12 @@ public class StreamManager {
 					for (StreamManager.UnackedPacket unacked : unacknowledgedStanzas) {
 						if (unacked.packet instanceof Message) {
 							Message m = (Message) unacked.packet;
+							if (m.getExtension("delay", "urn:xmpp:delay") == null) {
 								Element delayInformation = m.addChildElement("delay", "urn:xmpp:delay");
 								delayInformation.addAttribute("stamp", XMPPDateTimeFormat.format(unacked.timestamp));
 								delayInformation.addAttribute("from", serverAddress.toBareJID());
 							}
+						}
 						router.route(unacked.packet);
 					}
 				}