Revert to fulls for boths tests if delta fails.

bin/cros_au_test_harness.py

 #!/usr/bin/python
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import optparse
 import os
 import sys
 import unittest
@@ skipping 154 matching lines @@
     # don't pass many tests.
     self.PrepareBase()
     # TODO(sosa): move to 100% once we start testing using the autotest paired
     # with the dev channel.
     percent_passed = self.VerifyImage(10)
 
     if self.use_delta_updates: self.source_image = base_image_path
 
     # 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
 
     # Update from - same percentage should pass that originally passed.
     Info('Updating from updated image back to base image and wiping stateful.')
     self.UpdateImage(base_image_path, 'clean')
     self.VerifyImage(percent_passed)
 
 
@@ skipping 159 matching lines @@
     else:
       remote = options.remote
 
     suite = unittest.TestLoader().loadTestsFromTestCase(RealAUTest)
     test_result = unittest.TextTestRunner(verbosity=2).run(suite)
   else:
     parser.error('Could not parse harness type %s.' % options.type)
 
   if not test_result.wasSuccessful():
     Die('Test harness was not successful')