Fix range deletion covering key in same SST file
Fix range deletion covering key in same SST file

Summary:
AddTombstones() needs to be before t->Get(), oops :'(
Closes https://github.com/facebook/rocksdb/pull/1576

Differential Revision: D4241041

Pulled By: ajkr

fbshipit-source-id: 781ceea

bbiao/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,vmx/rocksdb,Andymic/rocksdb,vmx/rocksdb,bbiao/rocksdb,bbiao/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,wat-ze-hex/rocksdb,bbiao/rocksdb,Andymic/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,bbiao/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,vmx/rocksdb,vmx/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,wat-ze-hex/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,vmx/rocksdb,bbiao/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb