Fix a bug in TaskStackBuilder where task stack PendingIntents would

not clear tasks properly.

Change-Id: I5a7918fa5e400c160409a45d3e00b32f6f4809aa

core/java/android/app/TaskStackBuilder.java

@@ -206,7 +206,15 @@ public class TaskStackBuilder implements Iterable<Intent> {
      * @return The obtained PendingIntent
      */
     public PendingIntent getPendingIntent(int requestCode, int flags) {
+        if (mIntents.isEmpty()) {
+            throw new IllegalStateException(
+                    "No intents added to TaskStackBuilder; cannot getPendingIntent");
+        }
+
         Intent[] intents = mIntents.toArray(new Intent[mIntents.size()]);
+        intents[0].addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
+                Intent.FLAG_ACTIVITY_CLEAR_TASK |
+                Intent.FLAG_ACTIVITY_TASK_ON_HOME);
         return PendingIntent.getActivities(mSourceContext, requestCode, intents, flags);
     }
 }