This is basically a request to fix SERVER-4225 for pymongo

To reproduce:

• Start a mongod from scratch (no DB files/no users) with --auth
  [shell] mongod --auth

• Connect from pymongo on localhost and add an admin user
  conn = Connection()
  admin_db = conn['admin']
  admin_db.addUser('foo' , '123')

This will add the user foo but will raise an OperationFailure "need to login" error