Merge remote-tracking branch 'origin/6.2.1' into 7.1.5

src/Umbraco.Web/Scheduling/KeepAlive.cs

@@ -11,12 +11,7 @@ namespace Umbraco.Web.Scheduling
         public static void Start(object sender)
         {
             using (DisposableTimer.DebugDuration<KeepAlive>(() => "Keep alive executing", () => "Keep alive complete"))
-            {
-                //NOTE: sender will be the umbraco ApplicationContext
-
-                var appContext = sender as ApplicationContext;
-                if (appContext == null) return;
-
+            {                
                 var umbracoBaseUrl = ServerEnvironmentHelper.GetCurrentServerUmbracoBaseUrl();
 
                 var url = string.Format("{0}/ping.aspx", umbracoBaseUrl);