Bug 1434361: Inherit optimization of signing tasks from upstream task; r=aki

Differential Revision: https://phabricator.services.mozilla.com/D508

--HG--
extra : rebase_source : 0f05a8ed1bb9d35816db1418e5094338d76c0ab9

taskcluster/taskgraph/transforms/signing.py

@@ -146,6 +146,7 @@ def make_task_description(config, jobs):
             'dependencies': {job['depname']: dep_job.label},
             'attributes': attributes,
             'run-on-projects': dep_job.attributes.get('run_on_projects'),
+            'optimization': dep_job.optimization,
             'treeherder': treeherder,
             'routes': job.get('routes', []),
         }