Merge pull request #20919 from ktoso/agolubev-20843-Scan.in-cannot-pull-closed-port-agolubev

Agolubev 20843 scan.in cannot pull closed port agolubev

akka-stream/src/main/scala/akka/stream/impl/fusing/Ops.scala

@@ -315,7 +315,16 @@ final case class Scan[In, Out](zero: Out, f: (Out, In) ⇒ Out) extends GraphSta
           setHandlers(in, out, self)
         }
       })
-      setHandler(in, totallyIgnorantInput)
+
+      setHandler(in, new InHandler {
+        override def onPush(): Unit = ()
+        override def onUpstreamFinish(): Unit = setHandler(out, new OutHandler {
+          override def onPull(): Unit = {
+            push(out, aggregator)
+            completeStage()
+          }
+        })
+      })
 
       override def onPull(): Unit = pull(in)
       override def onPush(): Unit = {