Let the client do funny things with authname in startSession().

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5839 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/server/ClientManager.java

@@ -436,7 +436,9 @@ public class ClientManager
 
             // map their client instance
             synchronized (_usermap) {
-                _usermap.put(authname, client);
+                // we refetch the authname from the client for use in the map in case it decides to
+                // do something crazy like rewrite it in startSession()
+                _usermap.put(client.getAuthName(), client);
             }
         }