Revert to fulls for boths tests if delta fails.

bin/cros_au_test_harness.py

Index: bin/cros_au_test_harness.py
diff --git a/bin/cros_au_test_harness.py b/bin/cros_au_test_harness.py
index fdd4c0e23fe5ae81666c3743432887e07f5beea3..2c0eb2d5e272597bcdc55314a48d349f5d72a659 100755
--- a/bin/cros_au_test_harness.py
+++ b/bin/cros_au_test_harness.py
@@ -172,7 +172,17 @@ class AUTest(object):
 
     # Update to - all tests should pass on new image.
     Info('Updating from base image on vm to target image and wiping stateful.')
-    self.UpdateImage(target_image_path, 'clean')
+    try:
+      self.UpdateImage(target_image_path, 'clean')
+    except:
+      if self.use_delta_updates:
+        Warning('Delta update failed, disabling delta updates and retrying.')
+        self.use_delta_updates = False
+        self.source_image = ''
+        self.UpdateImage(target_image_path)
+      else:
+        raise
+
     self.VerifyImage(100)
 
     if self.use_delta_updates: self.source_image = target_image_path