MDEV-27244 Table corruption upon adding serial data type

MDEV-25803 excluded some cases from key sort upon alter table. That
particularly depends on ALTER_ADD_INDEX flag. Creating a column of
SERIAL data type missed that flag. Though equivalent operation

  alter table t1 add x bigint unsigned not null auto_increment unique;

has ALTER_ADD_INDEX flag.

mysql-test/suite/versioning/r/partition.result

@@ -746,4 +746,13 @@ explain partitions select * from t1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	pn	#	NULL	NULL	NULL	NULL	#	#
 drop table t1;
+#
+# MDEV-27244 Table corruption upon adding serial data type
+#
+create table t1 (f int, key(f)) with system versioning
+partition by system_time limit 10 (partition p0 history, partition pn current);
+alter table t1 add x serial;
+alter table t1 add partition (partition p1 history);
+alter table t1 add partition (partition p2 history);
+drop table t1;
 # End of 10.3 tests

mysql-test/suite/versioning/t/partition.test

@@ -727,6 +727,16 @@ explain partitions select * from t1 for system_time as of '2000-01-01 02:00:00';
 explain partitions select * from t1;
 drop table t1;
 
+--echo #
+--echo # MDEV-27244 Table corruption upon adding serial data type
+--echo #
+create table t1 (f int, key(f)) with system versioning
+partition by system_time limit 10 (partition p0 history, partition pn current);
+alter table t1 add x serial;
+alter table t1 add partition (partition p1 history);
+alter table t1 add partition (partition p2 history);
+drop table t1;
+
 --echo # End of 10.3 tests
 
 --source suite/versioning/common_finish.inc

sql/sql_yacc.yy

@@ -6783,6 +6783,7 @@ field_type_or_serial:
             Lex->last_field->set_handler(&type_handler_longlong);
             Lex->last_field->flags|= AUTO_INCREMENT_FLAG | NOT_NULL_FLAG
                                      | UNSIGNED_FLAG | UNIQUE_KEY_FLAG;
+            Lex->alter_info.flags|= ALTER_ADD_INDEX;
           }
           opt_serial_attribute
         ;

sql/sql_yacc_ora.yy

@@ -6625,6 +6625,7 @@ field_type_or_serial:
             Lex->last_field->set_handler(&type_handler_longlong);
             Lex->last_field->flags|= AUTO_INCREMENT_FLAG | NOT_NULL_FLAG
                                      | UNSIGNED_FLAG | UNIQUE_KEY_FLAG;
+            Lex->alter_info.flags|= ALTER_ADD_INDEX;
           }
           opt_serial_attribute
         ;