Merge "Fix back popping the back stack too much."
diff --git a/core/java/android/app/Activity.java b/core/java/android/app/Activity.java
index 3318bb1..d7bab1b 100644
--- a/core/java/android/app/Activity.java
+++ b/core/java/android/app/Activity.java
@@ -2072,7 +2072,7 @@
      * to pop, else false.
      */
     public boolean popBackStack() {
-        return popBackStack(null, -1);
+        return popBackStack(null, 0);
     }
 
     /**