Fix non-deterministic failure in backupable_db_test
Fix non-deterministic failure in backupable_db_test

Summary: FailOverwritingBackups has unexpected results when auto-compaction runs.

Test Plan: ran test a bunch of times

Reviewers: IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47181

tsheasha/rocksdb,kaschaeffer/rocksdb,norton/rocksdb,facebook/rocksdb,biddyweb/rocksdb,ryneli/rocksdb,wat-ze-hex/rocksdb,OverlordQ/rocksdb,wenduo/rocksdb,norton/rocksdb,RyanTech/rocksdb,JackLian/rocksdb,tsheasha/rocksdb,SunguckLee/RocksDB,wenduo/rocksdb,caijieming-baidu/rocksdb,hobinyoon/rocksdb,OverlordQ/rocksdb,norton/rocksdb,caijieming-baidu/rocksdb,tsheasha/rocksdb,geraldoandradee/rocksdb,ryneli/rocksdb,Andymic/rocksdb,bbiao/rocksdb,JackLian/rocksdb,wenduo/rocksdb,Vaisman/rocksdb,JackLian/rocksdb,hobinyoon/rocksdb,caijieming-baidu/rocksdb,JackLian/rocksdb,vmx/rocksdb,wenduo/rocksdb,kaschaeffer/rocksdb,facebook/rocksdb,wat-ze-hex/rocksdb,jalexanderqed/rocksdb,hobinyoon/rocksdb,wenduo/rocksdb,caijieming-baidu/rocksdb,jalexanderqed/rocksdb,ryneli/rocksdb,hobinyoon/rocksdb,RyanTech/rocksdb,facebook/rocksdb,kaschaeffer/rocksdb,kaschaeffer/rocksdb,luckywhu/rocksdb,Andymic/rocksdb,luckywhu/rocksdb,flabby/rocksdb,ryneli/rocksdb,norton/rocksdb,bbiao/rocksdb,flabby/rocksdb,wat-ze-hex/rocksdb,SunguckLee/RocksDB,Vaisman/rocksdb,facebook/rocksdb,kaschaeffer/rocksdb,geraldoandradee/rocksdb,caijieming-baidu/rocksdb,vmx/rocksdb,Vaisman/rocksdb,luckywhu/rocksdb,tsheasha/rocksdb,ryneli/rocksdb,geraldoandradee/rocksdb,Andymic/rocksdb,wenduo/rocksdb,tsheasha/rocksdb,OverlordQ/rocksdb,vmx/rocksdb,RyanTech/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,tsheasha/rocksdb,flabby/rocksdb,wenduo/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,hobinyoon/rocksdb,flabby/rocksdb,caijieming-baidu/rocksdb,flabby/rocksdb,jalexanderqed/rocksdb,caijieming-baidu/rocksdb,OverlordQ/rocksdb,RyanTech/rocksdb,Andymic/rocksdb,Andymic/rocksdb,Vaisman/rocksdb,norton/rocksdb,biddyweb/rocksdb,vmx/rocksdb,luckywhu/rocksdb,biddyweb/rocksdb,bbiao/rocksdb,jalexanderqed/rocksdb,RyanTech/rocksdb,hobinyoon/rocksdb,geraldoandradee/rocksdb,hobinyoon/rocksdb,kaschaeffer/rocksdb,OverlordQ/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,JackLian/rocksdb,geraldoandradee/rocksdb,ryneli/rocksdb,jalexanderqed/rocksdb,geraldoandradee/rocksdb,norton/rocksdb,wenduo/rocksdb,facebook/rocksdb,facebook/rocksdb,luckywhu/rocksdb,luckywhu/rocksdb,kaschaeffer/rocksdb,JackLian/rocksdb,Andymic/rocksdb,bbiao/rocksdb,hobinyoon/rocksdb,facebook/rocksdb,wat-ze-hex/rocksdb,wat-ze-hex/rocksdb,OverlordQ/rocksdb,vmx/rocksdb,RyanTech/rocksdb,tsheasha/rocksdb,ryneli/rocksdb,jalexanderqed/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,geraldoandradee/rocksdb,norton/rocksdb,Vaisman/rocksdb,Andymic/rocksdb,norton/rocksdb,luckywhu/rocksdb,bbiao/rocksdb,tsheasha/rocksdb,facebook/rocksdb,vmx/rocksdb,biddyweb/rocksdb,OverlordQ/rocksdb,flabby/rocksdb,flabby/rocksdb,RyanTech/rocksdb,Vaisman/rocksdb,biddyweb/rocksdb,Vaisman/rocksdb,wat-ze-hex/rocksdb,biddyweb/rocksdb,JackLian/rocksdb,biddyweb/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,SunguckLee/RocksDB,jalexanderqed/rocksdb