Added security fix.

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/trunk@5097 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/wildfire/ClientSession.java

@@ -660,8 +660,9 @@ public class ClientSession extends Session {
             // The client is available
             sessionManager.sessionAvailable(this);
             wasAvailable = true;
-        }
-        else if (oldPresence.getPriority() != this.presence.getPriority()) {
+        } else
+        if (this.presence.isAvailable() && oldPresence.getPriority() != this.presence.getPriority())
+        {
             // The client has changed the priority of his presence
             sessionManager.changePriority(getAddress(), this.presence.getPriority());
         }