Bug #13437 Partitions: table files can be same as partition files

Description:
I can create a table named tm_p0 which uses tm_p0.MYD and tm_p0.MYI.
I can create a partition named tm with a partition p0 -- which
uses tm_p0.MYD and tm_p0.MYI. So when I insert into tm_p0, the
row also goes into tm. 

How to repeat:
mysql> CREATE TABLE tm_p0 (s1 INT);
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE tm (s1 INT) PARTITION BY KEY (s1);
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO tm VALUES (0);
Query OK, 1 row affected (0.00 sec)

mysql> SELECT * FROM tm_p0;
+------+
| s1   |
+------+
|    0 |
+------+
1 row in set (0.00 sec)

Changed category to Server/Partitioning.

Changed from _ between table and partition name to #P# and to
#SP# between partition and subpartition name
Given that # is not allowed in table names this should now make it safe

Patch pushed and will appear in 5.1.6

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Additional info:

Documented as incompatible feature change in 5.1.6 changelog. Closed.