gistfile1.diff

@@ -367,8 +371,10 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
     // specific writer, then it would cause it to never start
     // flowing again.
     // So, if this is awaiting a drain, then we just call it now.
-    // If we don't know, then assume that we are waiting for one.
-    if (!dest._writableState || dest._writableState.needDrain)
+    // If we don't know, then assume that we are not
+    // waiting for one. If we don't know it's the writer's
+    // responsibility to manage drain state.
+    if (dest._writableState && dest._writableState.needDrain)
       ondrain();
   }

gistfile2.diff

@@ -496,6 +502,7 @@ Readable.prototype.unpipe = function(dest) {
     state.pipes = null;
     state.pipesCount = 0;
     this.removeListener('readable', pipeOnReadable);
+    state.flowing = false;
     if (dest)
       dest.emit('unpipe', this);
     return this;
@@ -510,6 +517,7 @@ Readable.prototype.unpipe = function(dest) {
     state.pipes = null;
     state.pipesCount = 0;
     this.removeListener('readable', pipeOnReadable);
+    state.flowing = false;