Return a :class:`JobStatus` instance from its string representation.

def from_string(cls, s):
        """Return a :class:`JobStatus` instance from its string representation."""
        for num, text in cls._STATUS_TABLE.items():
            if text == s: return cls(num)
        else:
            #raise ValueError("Wrong string %s" % s)
            logger.warning("Got unknown status: %s" % s)
            return cls.from_string("UNKNOWN")