Take a string as returned by get_ident and return a job,
        based on the class representation and the job's pk from the ident

def get_from_ident(self, ident):
        """
        Take a string as returned by get_ident and return a job,
        based on the class representation and the job's pk from the ident
        """
        model_repr, job_pk = ident.split(':', 1)
        klass = import_class(model_repr)
        return klass.get(job_pk)