Configurable isolation levels: read-committed and repeatable-read
User request: Implement something like JDBC's read-committed and repeatable-read isolation levels.
BitsyRetryException is predictably thrown on commits involving changed vertices and edges. But the rules for the version returned on a query is not clear. Sometimes the system returns the version from the last commit, and sometimes it returns the previously queried version in the same transaction. This behavior must be configurable.