'Skip nodes that have already been attempted.'

def backend_passes(self, backend_state, filter_properties):

    attempted = filter_properties.get('retry')
    if (not attempted):
        LOG.debug('Re-scheduling    is    disabled.')
        return True
    backends = attempted.get('backends', attempted.get('hosts', []))
    backend = backend_state.backend_id
    passes = (backend not in backends)
    pass_msg = ('passes' if passes else 'fails')
    LOG.debug('Backend    %(backend)s    %(pass_msg)s.        Previously    tried    backends:    %(backends)s', {'backend': backend, 'pass_msg': pass_msg, 'backends': backends})
    return passes
