Fix race in rpl.rpl_checksum.

mysql-test/suite/rpl/r/rpl_checksum.result

@@ -87,8 +87,7 @@ include/stop_slave.inc
 create table t2 (a int);
 set @@global.debug_dbug='d,simulate_checksum_test_failure';
 start slave io_thread;
-include/wait_for_slave_io_error.inc [errno=1595]
-Last_IO_Error = 'Relay log write failure: could not queue event from master'
+include/wait_for_slave_io_error.inc [errno=1595,1913]
 set @@global.debug_dbug='';
 start slave io_thread;
 include/wait_for_slave_param.inc [Read_Master_Log_Pos]

mysql-test/suite/rpl/t/rpl_checksum.test

@@ -143,8 +143,12 @@ connection slave;
 # instruction to io thread
 set @@global.debug_dbug='d,simulate_checksum_test_failure';
 start slave io_thread;
---let $slave_io_errno= 1595
---let $show_slave_io_error= 1
+# When the checksum error is detected, the slave sets error code 1913
+# (ER_NETWORK_READ_EVENT_CHECKSUM_FAILURE) in queue_event(), then immediately
+# sets error 1595 (ER_SLAVE_RELAY_LOG_WRITE_FAILURE) in handle_slave_io().
+# So we usually get 1595, but it is occasionally possible to get 1913.
+--let $slave_io_errno= 1595,1913
+--let $show_slave_io_error= 0
 source include/wait_for_slave_io_error.inc;
 set @@global.debug_dbug='';