Summary: Broke transaction locking in 4.4 in D52197. Will cherry-pick this change into 4.4 (which hasn't yet been fully released). Repro'd using db_bench.
Test Plan: unit tests and db_Bench
Reviewers: sdong, yhchiang, kradhakrishnan, ngbronson
Reviewed By: ngbronson
Subscribers: ngbronson, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D54021
d08d50295c