MRC: fixed issue w/ "finalized but not freed" buffers. This could occur if an...

MRC: fixed issue w/ "finalized but not freed" buffers. This could occur if an exception was thrown while iterating over a database index.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3429 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534