Bug#38540 rpl_server_id2 uses show slave status unnecessarily
            
Slave did not perform any event recorded into the relay log from some
different master when it was started with --replicate-same-server-id.
The reason appeared to be a consequence of BUG#38734 which stopped the
sql thread at its startup time.
      
The real fixes for the current bug are in the patch for BUG#38734.
This changeset carries only a regression test for the bugs.  Bug#38540
gets fixed too by means of eliminating an extra show slave status.


mysql-test/suite/rpl/r/rpl_server_id2.result:
  Bug#38934 Bug#38540 changed results.
mysql-test/suite/rpl/t/disabled.def:
  rpl_server_id2 is re-enabled.
mysql-test/suite/rpl/t/rpl_server_id2.test:
  regression test for BUG#38734 is added.
  Bug#38540 requirement to get rid of show slave status is implemented.