func isMembersEqual(membs []client.Member, wmembs []client.Member) bool {
	sort.Sort(SortableMemberSliceByPeerURLs(membs))
	sort.Sort(SortableMemberSliceByPeerURLs(wmembs))
	for i := range membs {
		membs[i].ID = ""
	}
	return reflect.DeepEqual(membs, wmembs)
}
func isMembersEqual(membs []client.Member, wmembs []client.Member) bool {
	sort.Sort(SortableMemberSliceByPeerURLs(membs))
	sort.Sort(SortableMemberSliceByPeerURLs(wmembs))
	for i := range membs {
		membs[i].ID = ""
	}
	return reflect.DeepEqual(membs, wmembs)
}
// isMembersEqual checks whether two members equal except ID field.
// The given wmembs should always set ID field to empty string.