Keep original revision as a build property.

scripts/master/unittests/try_job_base_test.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """try_job_base.py testcases."""
 
 import unittest
 
 import test_env  # pylint: disable=W0611
 
 from master import try_job_base
 
 
 class PaseOptionsTest(unittest.TestCase):
   def setUp(self):
     self.DEFAULT = 'DEFAULT'
     self.VALID_KEYS = ['linux', 'linux_chromeos',  'mac', 'win']
 
   @staticmethod
   def _get_default():
     return {
         'bot': {},
         'branch': None,
         'clobber': False,
         'email': [],
         'issue': None,
         'name': 'Unnamed',
+        'orig_revision': None,
         'patch': None,
         'patchlevel': 0,
         'patchset': None,
         'project': None,
         'reason': 'John Doe: Unnamed',
         'requester': None,
         'repository': None,
         'revision': None,
         'root': None,
         'testfilter': [],
@@ skipping 174 matching lines @@
         'DUPE=dupe2\n')
     expected = {
         'foo': ['bar'],
         'DUPE': ['dupe1', 'dupe2'],
     }
     self.assertEquals(expected, try_job_base.text_to_dict(text))
 
 
 if __name__ == '__main__':
   unittest.main()