Bug #28839 Errors in strict mode silently stop SQL thread if --slave-skip-errors exists.

slave_sql thread calls thd->clear_error() to force error to be ignored,
though this method didn't clear thd->killed state, what causes
slave_sql thread to stop.

clear thd->killed state if we ignore an error

mysql-test/r/rpl_skip_error.result

@@ -14,3 +14,22 @@ n
 2
 3
 drop table t1;
+create table t1(a int primary key);
+insert into t1 values (1),(2);
+delete from t1 where @@server_id=1;
+set sql_mode=strict_trans_tables;
+select @@server_id;
+@@server_id
+1
+insert into t1 values (1),(2),(3);
+select @@server_id;
+@@server_id
+2
+select * from t1;
+a
+1
+2
+show slave status;
+Slave_IO_State	Master_Host	Master_User	Master_Port	Connect_Retry	Master_Log_File	Read_Master_Log_Pos	Relay_Log_File	Relay_Log_Pos	Relay_Master_Log_File	Slave_IO_Running	Slave_SQL_Running	Replicate_Do_DB	Replicate_Ignore_DB	Replicate_Do_Table	Replicate_Ignore_Table	Replicate_Wild_Do_Table	Replicate_Wild_Ignore_Table	Last_Errno	Last_Error	Skip_Counter	Exec_Master_Log_Pos	Relay_Log_Space	Until_Condition	Until_Log_File	Until_Log_Pos	Master_SSL_Allowed	Master_SSL_CA_File	Master_SSL_CA_Path	Master_SSL_Cert	Master_SSL_Cipher	Master_SSL_Key	Seconds_Behind_Master
+Waiting for master to send event	127.0.0.1	root	9306	1	master-bin.000001	843	slave-relay-bin.000003	981	master-bin.000001	Yes	Yes							0		0	843	981	None		0	No						0
+drop table t1;

mysql-test/t/rpl_skip_error.test

@@ -17,3 +17,22 @@ connection master;
 drop table t1;
 sync_with_master;
 # End of 4.1 tests
+
+#
+# #28839 Errors in strict mode silently stop SQL thread if --slave-skip-errors exists
+#
+create table t1(a int primary key);
+insert into t1 values (1),(2);
+delete from t1 where @@server_id=1;
+set sql_mode=strict_trans_tables;
+select @@server_id;
+insert into t1 values (1),(2),(3);
+sync_slave_with_master;
+connection slave;
+select @@server_id;
+select * from t1;
+show slave status;
+connection master;
+drop table t1;
+sync_with_master;
+# End of 5.0 tests

sql/log_event.cc

@@ -1964,6 +1964,7 @@ Default database: '%s'. Query: '%s'",
     {
       DBUG_PRINT("info",("error ignored"));
       clear_all_errors(thd, rli);
+      thd->killed= THD::NOT_KILLED;
     }
     /*
       Other cases: mostly we expected no error and get one.