Dispose Listeners if they fail to start

src/Microsoft.AspNet.Server.Kestrel/KestrelEngine.cs

@@ -91,11 +91,15 @@ namespace Microsoft.AspNet.Server.Kestrel
         public IDisposable CreateServer(string scheme, string host, int port, Func<Frame, Task> application)
         {
             var listeners = new List<Listener>();
+
+            try
+            {
                 foreach (var thread in Threads)
                 {
                     var listener = new Listener(Memory);
-                listener.StartAsync(scheme, host, port, thread, application).Wait();
+
                     listeners.Add(listener);
+                    listener.StartAsync(scheme, host, port, thread, application).Wait();
                 }
                 return new Disposable(() =>
                 {
@@ -105,5 +109,15 @@ namespace Microsoft.AspNet.Server.Kestrel
                     }
                 });
             }
+            catch
+            {
+                foreach (var listener in listeners)
+                {
+                    listener.Dispose();
+                }
+
+                throw;
+            }
+        }
     }
 }