HBASE-10897 On master start, deadlock if refresh UI

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1584091 13f79535-47bb-0310-9956-ffa450edef68

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterStatusServlet.java

@@ -72,7 +72,7 @@ public class MasterStatusServlet extends HttpServlet {
     Set<ServerName> deadServers = null;
     
     if(master.isActiveMaster()) {
-      if (master.getServerManager() == null) {
+      if (!master.isInitialized()) {
         response.sendError(503, "Master not ready");
         return;
       }