UPDATE produces a wrong result while modifying a PK on a LevelDB table

create table t2 (pk int primary key, a char(8)) engine=LevelDB;

# Query OK, 0 rows affected (0.03 sec)

insert into t2 values (1,'a'),(2,'b'),(3,'c'),(4,'d');

# Query OK, 4 rows affected (0.00 sec)

# Records: 4  Duplicates: 0  Warnings: 0

update t2 set pk=100, a = 'updated' where a in ('b','c');

# Query OK, 2 rows affected (0.00 sec)

# Rows matched: 2  Changed: 2  Warnings: 0

select * from t2;

+-----+---------+

| pk  | a       |

+-----+---------+

|   1 | a       |

|   2 | b       |

|   3 | c       |

|   4 | d       |

| 100 | updated |

+-----+---------+

5 rows in set (0.00 sec)

+-----+---------+

| pk  | a       |

+-----+---------+

|   1 | a       |

|   4 | d       |

| 100 | updated |

+-----+---------+

date: 2012-12-21 22:14:26 +0400

build-date: 2012-12-22 21:39:19 +0400

revno: 4477

branch: mysql-5.6-leveldb