[nurple]

This is a lot like how couchdb handles MVCC. There is a `_rev` field that represents some specific mutation of a document, old revisions stay available until compaction, and you will receive an error if you attempt to write to a document with a different revision than you read.

Snapshot isolation, after all, is basically a method for implementing MVCC. I guess it's no big surprise that this isolation level is problematic for people that don't implement the other half.