fixup! stream: consolidate common code from readable push and unshift helper functions

Author: wa-Nadoo

lib/internal/streams/readable.js

@@ -738,6 +738,7 @@ Readable.prototype.read = function(n) {
 
 function onEofChunk(stream, state) {
   debug('onEofChunk');
+  if ((state[kState] & kEnded) !== 0) return;
   const decoder = (state[kState] & kDecoder) !== 0 ? state[kDecoderValue] : null;
   if (decoder) {
     const chunk = decoder.end();