node: properly check uid when adding AsyncListener

Instead of checking the uid on the array index of the queue, instead the
object property "uid" was checked on the queue iteself. Because this
will always evaluate to "undefined" the same listener could be added
multiple times to the same context.

src/node.js

@@ -495,7 +495,7 @@
       var inQueue = false;
       // The asyncQueue will be small. Probably always <= 3 items.
       for (var i = 0; i < queue.length; i++) {
-        if (obj.uid === queue.uid) {
+        if (obj.uid === queue[i].uid) {
           inQueue = true;
           break;
         }

test/simple/test-asynclistener-pushlistener.js

@@ -0,0 +1,52 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var net = require('net');
+
+var listener0 = process.createAsyncListener({ create: function() { } });
+var listener1 = process.createAsyncListener({ create: function() { } });
+
+process.on('exit', function() {
+  assert.ok(listened);
+  console.log('ok');
+});
+
+var server = net.createServer(function(c) { });
+
+var listened = false;
+server.listen(common.PORT, function() {
+  var handle = server._handle;
+
+  handle.addAsyncListener(listener0);
+  handle.addAsyncListener(listener0);
+  handle.addAsyncListener(listener1);
+  handle.addAsyncListener(listener1);
+
+  assert.equal(handle._asyncQueue.length, 2);
+  assert.deepEqual(handle._asyncQueue[0], listener0);
+  assert.deepEqual(handle._asyncQueue[1], listener1);
+
+  listened = true;
+
+  server.close();
+});