There's currently a check in `TransportService.HandshakeResponse.isIncompatibleBuild` to stop ES with the same Version but different build hashes from joining a cluster. This needs to be relaxed for cloud deployments where Version is not applicable
server/src/main/java/org/elasticsearch/transport/TransportService.java
return size() > 100;
        }
    });
    public static final TransportInterceptor NOOP_TRANSPORT_INTERCEPTOR = new TransportInterceptor() {
    };
    
    private final Logger tracerLog;
    private final Tracer tracer;
    volatile String[] tracerLogInclude;
    volatile String[] tracerLogExclude;
    private final RemoteClusterService remoteClusterService;
    
    volatile DiscoveryNode localNode = null;
    private final Transport.Connection localNodeConnection = new Transport.Connection() {
        @Override
        public DiscoveryNode getNode() {
            return localNode;
        }
        @Override
        public TransportVersion getTransportVersion() {
            return TransportVersion.CURRENT;
        }
        @Override
        public void sendRequest(long requestId, String action, TransportRequest request, TransportRequestOptions options) {
            sendLocalRequest(requestId, action, request, options);
        }
        @Override
        public void addCloseListener(ActionListener<Void> listener) {}
        @Override
        public void addRemovedListener(ActionListener<Void> listener) {}