db.createReadStream(); db.put(..,..); // Synchronous race condition

if you create a read stream, and then do a put, that put will be returned by the read stream.
creating the performing the put any later, like in the next tick, and it will be okay.

I've added a test for 4 cases, where you do createReadStream then puts,
it only affects the case where the database is open, and then a puts happen immediately after creating the read stream.