Break config_default into master_site_configs.

masters/master.tryserver.chromium/master.cfg

 # -*- python -*-
 # ex: set syntax=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.
 
 # READ THIS:
 # See http://dev.chromium.org/developers/testing/chromium-build-infrastructure
 
 from buildbot.scheduler import Triggerable
 
 # These modules come from scripts, which must be in the PYTHONPATH.
 from master import master_config
 from master import master_utils
 from master import slaves_list
 from master.builders_pools import BuildersPools
 from master.factory import annotator_factory
 from master.factory import chromeos_factory
 from master.factory import chromium_factory
 from master.factory import swarm_factory
 from master.try_job_http import TryJobHTTP
 from master.try_job_rietveld import TryJobRietveld
 from master.try_job_svn import TryJobSubversion
 
 import config
+import master_site_config
 
-ActiveMaster = config.Master.TryServer
+ActiveMaster = master_site_config.TryServer
 
 
 MAIL_NOTIFIER = True
 UPDATE_CODEREVIEW = ActiveMaster.is_production_host
 LISTEN_TO_SVN = ActiveMaster.svn_url and ActiveMaster.is_production_host
 
 # This is the dictionary that the buildmaster pays attention to. We also use
 # a shorter alias to save typing.
 c = BuildmasterConfig = {}
 
@@ skipping 2042 matching lines @@
 ####### PROJECT IDENTITY
 
 # The 'projectURL' string will be used to provide a link
 # from buildbot HTML pages to your project's home page.
 c['projectURL'] = 'http://dev.chromium.org/developers/testing/try-server-usage'
 
 # Buildbot master url:
 c['buildbotURL'] = 'http://build.chromium.org/p/tryserver.chromium/'
 
 # vi: set ts=4 sts=2 sw=2 et: