`v` is a mongodb option but is not a valid as far as the pymongo api goes
I figure backgrounding can be optional since a user might want to guarantee that an index is established before proceeding with subsequent queries (better than having them continuously poll the server for index completion).  For small datasets (ie. the 5 or 10mb our users will be working with) a blocking operation would probably be preferable to having to poll, especially if its in a script/multiline command.