INSERT chooses wrong partition for RANGE partitioning by DECIMAL column

commit c3f35ea55a7150b186284e2ef717d12e6f81e13e

Author: Aleksey Midenkov

Date:   Wed Aug 28 11:57:16 2019 +0300

    MDEV-18501 Partition pruning doesn't work for historical queries (refactoring)

    SYSTEM_TYPE partitioning: COLUMN properties removed. Partitioning is

    now pure RANGE based on UNIX_TIMESTAMP(row_end).

    DECIMAL type is now allowed as RANGE partitioning, we can partition by

    UNIX_TIMESTAMP() (but not for DATETIME which depends on local timezone

    of course).

MariaDB [test]> create or replace table t (d decimal(2,1)) partition by range (d) (partition p1 values less than (10), partition p2 values less than (20));

Query OK, 0 rows affected (0.690 sec)

MariaDB [test]> insert into t values (9.9);

Query OK, 1 row affected (0.049 sec)

MariaDB [test]> select * from t partition (p1);

Empty set (0.000 sec)

MariaDB [test]> select * from t partition (p2);

+------+

| d    |

+------+

|  9.9 |

+------+

1 row in set (0.000 sec)

MariaDB [test]> create or replace table t (d decimal(2,1)) partition by range (d) (partition p1 values less than (10));

Query OK, 0 rows affected (0.639 sec)

MariaDB [test]> insert into t values (9.9);

ERROR 1526 (HY000): Table has no partition for value 10