(#2574) - fix new_edits=false race in leveldb

Test fails before, succeeds after. The failure only occurs in leveldb, and it throws exactly the error I was seeing.

Booyah.
So walk through this in your head and imagine what happens when you do `new_edits=false` PUTs for two docs A and B, in this order: A, B, A. Since the rev for A already exists, it just uses B's seq number, which is totally wrong.