Add ChromiumOS Trybot support.

scripts/master/try_job_base.py

 # Copyright (c) 2011 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 buildbot
 from buildbot.process.properties import Properties
 
 from twisted.python import log
@@ skipping 37 matching lines @@
     options.setdefault('name', 'Unnamed')
     options.setdefault('user', 'John Doe')
     options['email'] = [e for e in options.get('email', '').split(',') if e]
     for email in options['email']:
       if not TryJobBase._EMAIL_VALIDATOR.match(email):
         log.msg("'%s' is an invalid email address!" % email)
         raise BadJobfile("'%s' is an invalid email address!" % email)
 
     options.setdefault('patch', None)
     options.setdefault('root', None)
-    options.setdefault('clobber', False)
+    options.setdefault('clobber', None)
     # -pN argument to patch.
     options['patchlevel'] = int(options.get('patchlevel', 0))
     options.setdefault('branch', None)
     options.setdefault('revision', None)
     options.setdefault('reason', '%s: %s' % (options['user'], options['name']))
     options['testfilter'] = [
         i for i in options.get('testfilter', '').split(',') if i
     ]
     options.setdefault('project', self.pools.default_pool_name)
     options.setdefault('repository', None)
@@ skipping 14 matching lines @@
     return options
 
   def get_props(self, options):
     """Current job extra properties that are not related to the source stamp.
     Initialize with the Scheduler's base properties.
     """
     props = Properties()
     # TODO(maruel): BROKEN ON BULDBOT 0.8.4p1
     # pylint: disable=E1101
     props.updateFromProperties(self.properties)
-    props.setProperty('clobber', options['clobber'], 'Scheduler')
+    if options['clobber'] is not None:
+      props.setProperty('clobber', options['clobber'], 'Scheduler')
     if options['testfilter']:
       props.setProperty('testfilters', options['testfilter'], 'Scheduler')
     return props