def job_assign_filter(instance, field, old_value, new_value):
    """
    A custom setter for the JobState.job.

    .. warning::
        This setter should not exist. job attribute should be read-only. This
        is a temporary kludge to get session restoring over DBus working. Once
        a solution that doesn't involve setting a JobState's job attribute is
        implemented, please remove this awful method.
    """
    return new_value
