Fixed rpl.rpl_mariadb_slave_capability.result file

The cause was an uninitalized variable on the slave when reading a dummy
event that can only be generated by the test.

Fixed by ensuring that flag2 is always initialized.
Fixed also some indentation issues and improved comments.

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

@@ -40,12 +40,12 @@ a
 1
 include/show_events.inc
 Log_name	Pos	Event_type	Server_id	End_log_pos	Info
-slave-relay-bin.000005	#	Query	#	#	set foreign_key_checks=1, check_constraint_checks=1; BEGIN
+slave-relay-bin.000005	#	Query	#	#	BEGIN
 slave-relay-bin.000005	#	Annotate_rows	#	#	DELETE FROM t1
 slave-relay-bin.000005	#	Table_map	#	#	table_id: # (test.t1)
 slave-relay-bin.000005	#	Delete_rows_v1	#	#	table_id: # flags: STMT_END_F
 slave-relay-bin.000005	#	Query	#	#	COMMIT
-slave-relay-bin.000005	#	Query	#	#	set foreign_key_checks=1, check_constraint_checks=1; BEGIN
+slave-relay-bin.000005	#	Query	#	#	BEGIN
 slave-relay-bin.000005	#	Annotate_rows	#	#	INSERT INTO t1 /* A comment just to make the annotate event sufficiently long that the dummy event will need to get padded with spaces so that we can test that this works */ VALUES(1)
 slave-relay-bin.000005	#	Table_map	#	#	table_id: # (test.t1)
 slave-relay-bin.000005	#	Write_rows_v1	#	#	table_id: # flags: STMT_END_F
@@ -70,7 +70,7 @@ a
 2
 include/show_events.inc
 Log_name	Pos	Event_type	Server_id	End_log_pos	Info
-slave-relay-bin.000007	#	Query	#	#	set foreign_key_checks=1, check_constraint_checks=1; BEGIN
+slave-relay-bin.000007	#	Query	#	#	BEGIN
 slave-relay-bin.000007	#	Annotate_rows	#	#	INSERT INTO t1 VALUES(2)
 slave-relay-bin.000007	#	Table_map	#	#	table_id: # (test.t1)
 slave-relay-bin.000007	#	Write_rows_v1	#	#	table_id: # flags: STMT_END_F
@@ -137,7 +137,7 @@ a
 3
 include/show_events.inc
 Log_name	Pos	Event_type	Server_id	End_log_pos	Info
-slave-relay-bin.000008	#	Query	#	#	set foreign_key_checks=1, check_constraint_checks=1; BEGIN
+slave-relay-bin.000008	#	Query	#	#	BEGIN
 slave-relay-bin.000008	#	Annotate_rows	#	#	UPDATE t1 SET a = 3
 slave-relay-bin.000008	#	Table_map	#	#	table_id: # (test.t1)
 slave-relay-bin.000008	#	Update_rows_v1	#	#	table_id: # flags: STMT_END_F

sql/log_event.cc

@@ -1435,7 +1435,7 @@ Query_log_event::Query_log_event(const char* buf, uint event_len,
                                  Log_event_type event_type)
   :Log_event(buf, description_event), data_buf(0), query(NullS),
    db(NullS), catalog_len(0), status_vars_len(0),
-   flags2_inited(0), sql_mode_inited(0), charset_inited(0),
+   flags2_inited(0), sql_mode_inited(0), charset_inited(0), flags2(0),
    auto_increment_increment(1), auto_increment_offset(1),
    time_zone_len(0), lc_time_names_number(0), charset_database_number(0),
    table_map_for_update(0), master_data_written(0)

sql/log_event_client.cc

@@ -1868,9 +1868,10 @@ bool Query_log_event::print_query_header(IO_CACHE* file,
   }
 
   /*
-    If flags2_inited==0, this is an event from 3.23 or 4.0; nothing to
-    print (remember we don't produce mixed relay logs so there cannot be
-    5.0 events before that one so there is nothing to reset).
+    If flags2_inited==0, this is an event from 3.23 or 4.0 or a dummy
+    event from the mtr test suite; nothing to print (remember we don't
+    produce mixed relay logs so there cannot be 5.0 events before that
+    one so there is nothing to reset).
   */
   if (likely(flags2_inited)) /* likely as this will mainly read 5.0 logs */
   {
@@ -3761,6 +3762,7 @@ st_print_event_info::st_print_event_info()
   delimiter[0]= ';';
   delimiter[1]= 0;
   flags2_inited= 0;
+  flags2= 0;
   sql_mode_inited= 0;
   row_events= 0;
   sql_mode= 0;

sql/log_event_server.cc

@@ -1367,7 +1367,8 @@ Query_log_event::Query_log_event()
   Creates an event for binlogging
   The value for `errcode' should be supplied by caller.
 */
-Query_log_event::Query_log_event(THD* thd_arg, const char* query_arg, size_t query_length, bool using_trans,
+Query_log_event::Query_log_event(THD* thd_arg, const char* query_arg,
+                                 size_t query_length, bool using_trans,
 				 bool direct, bool suppress_use, int errcode)
 
   :Log_event(thd_arg,
@@ -1380,7 +1381,7 @@ Query_log_event::Query_log_event(THD* thd_arg, const char* query_arg, size_t que
    thread_id(thd_arg->thread_id),
    /* save the original thread id; we already know the server id */
    slave_proxy_id((ulong)thd_arg->variables.pseudo_thread_id),
-   flags2_inited(1), sql_mode_inited(1), charset_inited(1),
+   flags2_inited(1), sql_mode_inited(1), charset_inited(1), flags2(0),
    sql_mode(thd_arg->variables.sql_mode),
    auto_increment_increment(thd_arg->variables.auto_increment_increment),
    auto_increment_offset(thd_arg->variables.auto_increment_offset),
@@ -1685,15 +1686,18 @@ int Query_log_event::do_apply_event(rpl_group_info *rgi,
     {
       thd->slave_expected_error= expected_error;
       if (flags2_inited)
+      {
         /*
-          all bits of thd->variables.option_bits which are 1 in OPTIONS_WRITTEN_TO_BIN_LOG
-          must take their value from flags2.
+          all bits of thd->variables.option_bits which are 1 in
+          OPTIONS_WRITTEN_TO_BIN_LOG must take their value from
+          flags2.
         */
         thd->variables.option_bits= flags2|(thd->variables.option_bits & ~OPTIONS_WRITTEN_TO_BIN_LOG);
+      }
       /*
         else, we are in a 3.23/4.0 binlog; we previously received a
-        Rotate_log_event which reset thd->variables.option_bits and sql_mode etc, so
-        nothing to do.
+        Rotate_log_event which reset thd->variables.option_bits and
+        sql_mode etc, so nothing to do.
       */
       /*
         We do not replicate MODE_NO_DIR_IN_CREATE. That is, if the master is a