Stream should unpipe from Readable on destroy.

lib/index.js

@@ -379,6 +379,22 @@ _.seq = function () {
     };
 };
 
+function pipeReadable(xs, stream) {
+    // write any errors into the stream
+    xs.on('error', writeStreamError);
+    xs.pipe(stream);
+
+    // TODO: Replace with onDestroy in v3.
+    stream._destructors.push(function () {
+        xs.unpipe(stream);
+        xs.removeListener('error', writeStreamError);
+    });
+
+    function writeStreamError(err) {
+        stream.write(new StreamError(err));
+    }
+}
+
 function promiseGenerator(promise) {
     return _(function (push) {
         promise.then(function (value) {
@@ -561,11 +577,7 @@ function Stream(/*optional*/xs, /*optional*/ee, /*optional*/mappingHint) {
     else if (_.isObject(xs)) {
         // check to see if we have a readable stream
         if (_.isFunction(xs.on) && _.isFunction(xs.pipe)) {
-            // write any errors into the stream
-            xs.on('error', function (err) {
-                self.write(new StreamError(err));
-            });
-            xs.pipe(self);
+            pipeReadable(xs, self);
         }
         else if (_.isFunction(xs.then)) {
             //probably a promise

test/test.js

@@ -411,7 +411,7 @@ exports['constructor'] = {
         test.strictEqual(s, _(s));
         test.done();
     },
-    'from Readable stream with next function - issue #303': function (test) {
+    'from Readable with next function - issue #303': function (test) {
         var Readable = Stream.Readable;
 
         var rs = new Readable;
@@ -424,6 +424,25 @@ exports['constructor'] = {
             .toArray(this.tester(['a', 'b', 'c'], test));
         test.done();
     },
+    'from Readable - unpipes on destroy': function (test) {
+        var rs = streamify([1, 2, 3]);
+
+        var s = _(rs);
+        s.pull(valueEquals(test, 1));
+        s.destroy();
+
+        var writtenTo = false;
+        var write = s.write;
+        s.write = function () {
+            console.log('writtenTo');
+            writtenTo = true;
+            write.call(s, arguments);
+        };
+        s.emit('drain');
+
+        test.ok(!writtenTo, 'Drain should not cause write to be called.');
+        test.done();
+    },
     'throws error for unsupported object': function (test) {
         test.throws(function () {
             _({}).done(function () {});