The Twisted Transactor should offer an API for tracking retries

The storm.twisted.Transactor wrapper has support for retrying the wrapped function upon transaction failures, however there's no way for client code (and specifically the function being wrapped) to know if the function is being run for the first time or if it's a retry, and if so how many retries are left. For instance this can be useful for logging, so the wrapped function doesn't log false positives.