Before the patch, slaves only appear in the output of SHOW SLAVE HOSTS 
      when report-host option is set. If an expected slave does not appear in  
      the list, nobody knows whether the slave does not connect or has started
      without the "report-host" option. The output also contains a strange  
      field "Rpl_recovery_rank" which has never been implemented and the manual 
      of MySQL5.4 declares that the field has been removed from MySQL5.4.
                                        
      This patch is done with these,
      According to the manual of MySQL5.4, "Rpl_recovery_rank" is removed.
      Slaves will register themselves to master no matter if report_host option is set
      or not. When slaves are registering themselves, their Server_ids, report_host
      and other information are together sent to master. Sever_ids are never null 
      and is unique in one replication group. Slaves always can be identified with  
      different Server_ids no matter if report_host exists.