AS A INNODB PARTITTION.

PROBLEM
-------
The correct engine_type was not being set during 
rebuild of the partition due to which the handler
was always created with the default engine,
which is innodb for 5.5+ ,therefore even if the
table was myisam, after rebuilding the partitions
ended up as innodb partitions.

FIX
---
Set the correct engine type during rebuild.  

[Approved by mattiasj #rb3599]