MDEV-17377 invalid gap in auto-increment values after LOAD DATA

reset lex->many_values for LOAD DATA, as it's used for
auto-inc range size estimation.

mysql-test/r/auto_increment_ranges_innodb.result

@@ -264,3 +264,17 @@ delete from t1 where a=32767;
 insert into t1 values(NULL);
 ERROR 22003: Out of range value for column 'a' at row 1
 drop table t1;
+create table t1 (pk int auto_increment primary key, f varchar(20));
+insert t1 (f) values ('a'), ('b'), ('c'), ('d');
+select null, f into outfile 'load.data' from t1 limit 1;
+load data infile 'load.data' into table t1;
+insert t1 (f) values ('<===');
+select * from t1;
+pk	f
+1	a
+2	b
+3	c
+4	d
+5	a
+6	<===
+drop table t1;

mysql-test/t/auto_increment_ranges_innodb.test

@@ -5,3 +5,14 @@
 --source include/have_innodb.inc
 set default_storage_engine=innodb;
 --source auto_increment_ranges.inc
+
+#
+# MDEV-17377 invalid gap in auto-increment values after LOAD DATA
+#
+create table t1 (pk int auto_increment primary key, f varchar(20));
+insert t1 (f) values ('a'), ('b'), ('c'), ('d');
+select null, f into outfile 'load.data' from t1 limit 1;
+load data infile 'load.data' into table t1;
+insert t1 (f) values ('<===');
+select * from t1;
+drop table t1;

sql/sql_yacc.yy

@@ -12073,6 +12073,7 @@ load:
             lex->field_list.empty();
             lex->update_list.empty();
             lex->value_list.empty();
+            lex->many_values.empty();
           }
           opt_load_data_charset
           { Lex->exchange->cs= $14; }