swarming: add support for cipd on the server side

appengine/swarming/handlers_bot.py

Index: appengine/swarming/handlers_bot.py
diff --git a/appengine/swarming/handlers_bot.py b/appengine/swarming/handlers_bot.py
index 28a125698c9d85565a78f2f30b61e804fa7b12ab..be52a5cb697a71ccd18363cab9ecaf3ed9df9dc9 100644
--- a/appengine/swarming/handlers_bot.py
+++ b/appengine/swarming/handlers_bot.py
@@ -392,6 +392,13 @@ class BotPollHandler(_BotBaseHandler):
         'host': utils.get_versioned_hosturl(),
         'io_timeout': request.properties.io_timeout_secs,
         'inputs_ref': request.properties.inputs_ref,
+        'packages': [
+          {
+            'package_name': p.package_name,
+            'version': p.version,
+          }
+          for p in request.properties.packages
+        ],
         'task_id': task_pack.pack_run_result_key(run_result_key),
       },
     }