Keep original revision as a build property.

scripts/master/try_job_base.py

 # 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.
 
 import re
 import traceback
 import sys
 
 from buildbot.process.properties import Properties
 from buildbot.schedulers.trysched import TryBase
@@ skipping 110 matching lines @@
     for email in options['email']:
       # Access to a protected member XXX of a client class
       # pylint: disable=W0212
       if not TryJobBase._EMAIL_VALIDATOR.match(email):
         raise BadJobfile("'%s' is an invalid email address!" % email)
 
     flatten(options, 'patch', None)
     flatten(options, 'root', None)
     try_int(options, 'patchlevel', 0)
     flatten(options, 'branch', None)
+
     flatten(options, 'revision', None)
+    options.setdefault('orig_revision', options['revision'])
+
     flatten(options, 'reason', '%s: %s' % (options['user'], options['name']))
     try_bool(options, 'clobber', False)
 
     flatten(options, 'project', pools.default_pool_name if pools else None)
     flatten(options, 'repository', None)
 
     # Code review info. Enforce numbers.
     try_int(options, 'patchset', None)
     try_int(options, 'issue', None)
 
@@ skipping 57 matching lines @@
   def parse_options(self, options):
     return parse_options(options, self.valid_builders, self.pools)
 
   def get_props(self, builder, options):
     """Current job extra properties that are not related to the source stamp.
     Initialize with the Scheduler's base properties.
     """
     keys = (
       'clobber',
       'issue',
+      'orig_revision',
       'patch_url',
       'patchset',
       'requester',
       'rietveld',
       'root',
       'try_job_key',
     )
     # All these settings have no meaning when False or not set, so don't set
     # them in that case.
     properties = dict((i, options[i]) for i in keys if options.get(i))
@@ skipping 66 matching lines @@
                         new_value > self._last_lkgr[project]):
         self._last_lkgr[project] = new_value
       options['revision'] = self._last_lkgr[project] or 'HEAD'
 
     def Failure(result):
       options['revision'] = self._last_lkgr[project] or 'HEAD'
 
     connection = client.getPage(last_good_url, agent='buildbot')
     connection.addCallbacks(Success, Failure)
     return connection