Summary:
WriteBatchWithIndex::GetFromBatchAndDB only works correctly for overwrite_key=false. Transactions use overwrite_key=true (since WriteBatchWithIndex::GetIteratorWithBase only works when overwrite_key=true). So currently, Transactions could return incorrectly merged results when calling Get/GetForUpdate().
Until a permanent fix can be put in place, Transaction::Get[ForUpdate] and WriteBatchWithIndex::GetFromBatch[AndDB] will now return MergeInProgress if the most recent write to a key in the batch is a Merge.
Test Plan: more tests
Reviewers: sdong, yhchiang, rven, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D47817
03b08ba9a9