Code review comment for lp:~pbeaman/akiban-persistit/remove_fast_index_ratio

Yup, there was an actual bug in the modified version of Buffer. As a consequence, FastIndexTest#testFastIndexRecompute throw an AssertionError. But FastIndexTest was not written defensively to remove buffer claims even in the event of an error, so the tearDown() method, which calls Persistit#close() hung due to inability to claim the page.

Three issues to resolve:

1. New bug in Buffer (rewrite failed to recompute an invalid FastIndex in the getFastIndex() method).

2. FastIndexTest needs try/finally blocks to ensure the buffer gets released.

3. Volume#close() needs to time out if unable to invalidate the volume within a reasonable length of time.

Adding this changes and resubmitting.