Merge pull request #9403 from jpbetz/automated-cherry-pick-of-#9336-origin-release-3.2

Automated cherry pick of #9336

proxy/httpproxy/reverse.go

@@ -119,6 +119,7 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 			case <-closeCh:
 				atomic.StoreInt32(&requestClosed, 1)
 				plog.Printf("client %v closed request prematurely", clientreq.RemoteAddr)
+				cancel()
 			case <-completeCh:
 			}
 		}()