Summary:
This reverts commit d70011bccc9a9383f368e509671d5e4eb8f3a2c2. The commit is causing some stress test failure due to unexpected Status::MergeInProgress() return for some keys.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6401
Differential Revision: D19826623
Pulled By: anand1976
fbshipit-source-id: edd634cede9cb7bdd2cb8f46e662ea709b16d2f1