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
try (ThreadContext.StoredContext ignore = contextSupplier.get()) {
                delegate.handleResponse(response);
            }
        }
        @Override
        public void handleException(TransportException exp) {
            if (handler != null) {
                handler.cancel();
            }
            try (ThreadContext.StoredContext ignore = contextSupplier.get()) {
                delegate.handleException(exp);
            }
        }
        @Override
        public String executor() {
            return delegate.executor();
        }
        @Override
        public String toString() {
            return getClass().getName() + "/" + delegate.toString();
        }
        void setTimeoutHandler(TimeoutHandler timeoutHandler) {
            this.handler = timeoutHandler;
        }
        
        TransportResponseHandler<T> unwrap() {
            return delegate;
        }
    }
    static class DirectResponseChannel implements TransportChannel {