Add decorations to bot names for modifying parts of try sets.

scripts/master/try_job_base_bb7.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 os
 
 from buildbot import buildset
 from buildbot.changes.changes import Change
 from buildbot.scheduler import BadJobfile
 from buildbot.scheduler import TryBase  # pylint: disable=W0611
@@ skipping 88 matching lines @@
       log.msg('%s reports a bad job connection' % (self))
       log.err()
       return http.BAD_REQUEST
     reason = "'%s' try job" % buildset_id
     # Send one build request per builder, otherwise the cancelation logic
     # doesn't work.
     build_sets = []
     assert isinstance(builder_names, list)
     for builder_name in builder_names:
       build_set = buildset.BuildSet(
-          [builder_name],
+          builder_name.split(':', 1)[0:1],
           jobstamp,
           reason=reason,
           bsid=buildset_id,
-          properties=props)
+          properties=self.parse_decoration(props,
+              ''.join(builder_name.split(':', 1)[1:])))
       build_sets.append(build_set)
       self.CancelJobsMatching(build_set, builder_name)
     for build_set in build_sets:
       # Type inference error.
       # pylint: disable=E1101
       self.parent.submitBuildSet(build_set)
     return http.OK