Whilst percent strings can't, calls to format can.

So:

    log.debug("Unexpected, got {got}".format(got=got))

Or, to just use the available locals to automatically fill that in for you:

    log.debug("Unexepected, got {got}".format(**locals()))

Or if you want both globals and locals with a preference for locals:

    log.debug("Unexepected, got {got}".format(**{**globals(), **locals()}))