BUG#32709: Assertion failed: trx_data->empty(), file log.cc

Incremental fixes: updating a comment and fixing a result file.

sql/sql_class.h:
  Changing comment.

mysql-test/suite/rpl_ndb/r/rpl_row_basic_7ndb.result

@@ -520,3 +520,10 @@ INSERT INTO t7 VALUES (1, "", 1);
 INSERT INTO t7 VALUES (2, repeat(_utf8'a', 255), 2);
 Comparing tables master:test.t7 and slave:test.t7
 drop table t1, t2, t3, t4, t5, t6, t7;
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE='NDB' ;
+INSERT INTO t1 VALUES (1), (2), (3);
+UPDATE t1 SET a = 10;
+ERROR 23000: Duplicate entry '10' for key 'PRIMARY'
+INSERT INTO t1 VALUES (4);
+Comparing tables master:test.t1 and slave:test.t1
+drop table t1;

sql/sql_class.h

@@ -1363,7 +1363,11 @@ public:
   int binlog_remove_pending_rows_event(bool clear_maps);
 
 private:
-  uint binlog_table_maps; // Number of table maps currently in the binlog
+  /*
+    Number of outstanding table maps, i.e., table maps in the
+    transaction cache.
+  */
+  uint binlog_table_maps;
 
   enum enum_binlog_flag {
     BINLOG_FLAG_UNSAFE_STMT_PRINTED,