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Rx.NET/Source/src/System.Reactive/Linq/Observable/Zip.cs

@@ -524,6 +524,9 @@ namespace System.Reactive.Linq.ObservableImpl
 
         public override void OnCompleted()
         {
+            // Calling Dispose() here would clear the queue prematurely.
+            // We only need to dispose the IDisposable of the upstream,
+            // which is done by SafeObserver.Dispose(bool).
             base.Dispose(true);
 
             lock (_gate)