Bug 1391789 - Set relengapi-proxy on correct object; r=bustage

This corrects a bug introduced in 265873cf1388.

MozReview-Commit-ID: LkZlTVAM17E

--HG--
extra : rebase_source : bf442e620abd6b47adee3d4c56e6f0c19964aea1

taskcluster/taskgraph/transforms/job/common.py

@@ -149,7 +149,7 @@ def docker_worker_add_tooltool(config, job, taskdesc, internal=False):
         'TOOLTOOL_CACHE': '/home/worker/tooltool-cache',
     })
 
-    job['worker']['relengapi-proxy'] = True
+    taskdesc['worker']['relengapi-proxy'] = True
     taskdesc['scopes'].extend([
         'docker-worker:relengapi-proxy:tooltool.download.public',
     ])