=tck fixes minor misalignment between code and comment, found via .NET port

Semantics remain exacly the same, the error we're testing here is about
signaling one more element if request comes in again (which we'll do
anyway, regardless of status of this flag)

Author: ktoso

tck/src/test/java/org/reactivestreams/tck/PublisherVerificationTest.java

@@ -241,6 +241,7 @@ public void required_spec107_mustNotEmitFurtherSignalsOnceOnCompleteHasBeenSigna
                 // but keep signalling data if more demand comes in anyway!
                 if (!completed) {
                   s.onComplete();
+                  completed = true;
                 }
 
               }