swarming: add transaction_id to tasks.new request

appengine/swarming/server/task_request.py

Index: appengine/swarming/server/task_request.py
diff --git a/appengine/swarming/server/task_request.py b/appengine/swarming/server/task_request.py
index 8e2ecd98f8b398ea310a6ab108f92c6522d0cf48..afa27796e278877988d03ed1d22e7afdcfb48bb0 100644
--- a/appengine/swarming/server/task_request.py
+++ b/appengine/swarming/server/task_request.py
@@ -659,11 +659,12 @@ class TaskRequest(ndb.Model):
         acl.is_privileged_user() or
         self.authenticated == auth.get_current_identity())
 
-  def to_dict(self):
+  def to_dict(self, exclude=None):
     """Converts properties_hash to hex so it is json serializable."""
     # to_dict() doesn't recurse correctly into ndb.LocalStructuredProperty!
-    out = super(TaskRequest, self).to_dict(
-        exclude=['pubsub_auth_token', 'properties', 'service_account_token'])
+    exclude = exclude or []

[M-A Ruel, 2017/05/03 01:33:20]

generally prefer to take a copy of list passed as an input, so if it's a global
variable it is not modified. e.g.

exclude = (exclude or [])[:]

this is not efficient but this is python. :)

[nodir, 2017/05/05 18:11:38]

Done, dumb mistake

+    exclude.extend(['pubsub_auth_token', 'properties', 'service_account_token'])
+    out = super(TaskRequest, self).to_dict(exclude=exclude)
     out['properties'] = self.properties.to_dict()
     properties_hash = out['properties_hash']
     out['properties_hash'] = (