Summary:
Test failing due to a missing directory caused by a simple bug (did not run into this on my dev box since the path already existed).

We should look into deleting test::TmpDir() before each test run.

Test Plan: ran test

Reviewers: igor, yhchiang, meyering, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D36831