Bug #16530 DROP PARTITION fails with OS permissions error

Description:
mysql> CREATE TABLE employees2 (
    ->   id INT NOT NULL,
    ->   fname VARCHAR(50) NOT NULL,
    ->   lname VARCHAR(50) NOT NULL,
    ->   hired DATE NOT NULL
    -> )
    -> PARTITION BY RANGE( YEAR(hired) ) (
    ->   PARTITION p1 VALUES LESS THAN (1991),
    ->   PARTITION p2 VALUES LESS THAN (1996),
    ->   PARTITION p3 VALUES LESS THAN (2001),
    ->   PARTITION p4 VALUES LESS THAN (2005),
    ->   PARTITION p5 VALUES LESS THAN MAXVALUE
    -> );
Query OK, 0 rows affected (0.08 sec)

[inserted 10,000 rows using script]

mysql> SELECT COUNT(*) FROM employees2;
+----------+
| COUNT(*) |
+----------+
|    10000 |
+----------+
1 row in set (0.01 sec)

mysql> SELECT COUNT(*) FROM employees2 WHERE YEAR(hired) < 1991;
+----------+
| COUNT(*) |
+----------+
|     2286 |
+----------+
1 row in set (0.03 sec)                 

mysql> ALTER TABLE employees2 DROP PARTITION p1;
ERROR 6 (HY000): Error on delete of '.\part\employees2_p1.MYI' (Errcode: 13)

DB and table created by MySQL root. Table populated by script running running as MySQL root. Attempt to drop partition as MySQL root.

I checked permissions on the files and all parent directories in question. Owner is Administrators. All permissions (including Delete permissions) enabled for Everyone.

Server is installed in C:\mysql\bin.
Data directory is M:\mydata (different disk).

How to repeat:
See Description.

Suggested fix:
Allow MySQL user with appropriate permissions on the table to delete a partition.

Performed same test using 5.1.6-bk built 2006-01-16 on SuSE Linux 9.3, worked without issues.

This issue isn't more repeatable with current Windows source server:

c:\mysql\bin>mysql -uroot test
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1 to server version: 5.1.7-beta-nt-max-log

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> CREATE TABLE employees2 (
    -> id INT NOT NULL,
    -> fname VARCHAR(50) NOT NULL,
    -> lname VARCHAR(50) NOT NULL,
    -> hired DATE NOT NULL
    -> )
    -> PARTITION BY RANGE( YEAR(hired) ) (
    -> PARTITION p1 VALUES LESS THAN (1991),
    -> PARTITION p2 VALUES LESS THAN (1996),
    -> PARTITION p3 VALUES LESS THAN (2001),
    -> PARTITION p4 VALUES LESS THAN (2005),
    -> PARTITION p5 VALUES LESS THAN MAXVALUE
    -> );
Query OK, 0 rows affected (0.17 sec)

mysql> ALTER TABLE employees2 DROP PARTITION p1;
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> show create table employees2\G
*************************** 1. row ***************************
       Table: employees2
Create Table: CREATE TABLE `employees2` (
  `id` int(11) NOT NULL,
  `fname` varchar(50) NOT NULL,
  `lname` varchar(50) NOT NULL,
  `hired` date NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 PARTITION BY RANGE ( YEAR(hired)) (PARTITION p2 VALUES LESS THAN (1
996) ENGINE = MyISAM, PARTITION p3 VALUES LESS THAN (2001) ENGINE = MyISAM, PARTITION p4 VALUES LESS THAN
(2005) ENGINE = MyISAM, PARTITION p5 VALUES LESS THAN MAXVALUE ENGINE = MyISAM)
1 row in set (0.01 sec)

mysql>