Merge pull request #443 from smallrye/fix-uni-directsubscription

implementation/src/main/java/io/smallrye/mutiny/operators/UniSerializedSubscriber.java

@@ -46,7 +46,7 @@ public class UniSerializedSubscriber<T> implements UniSubscriber<T>, UniSubscrip
     public static <T> void subscribe(AbstractUni<T> source, UniSubscriber<? super T> subscriber) {
         UniSubscriber<? super T> actual = Infrastructure.onUniSubscription(source, subscriber);
         if (subscriber instanceof UniSerializedSubscriber) {
-            source.subscribing(subscriber);
+            source.subscribing(actual);
         } else {
             UniSerializedSubscriber<T> wrapped = new UniSerializedSubscriber<>(source, actual);
             wrapped.subscribe();