Bug 1776830 - part 4: Let multi_dep tasks override primary dep attributes

taskcluster/fenix_taskgraph/transforms/multi_dep.py

@@ -22,10 +22,11 @@ def build_name_and_attributes(config, tasks):
             dep_key: dep.label for dep_key, dep in _get_all_deps(task).items()
         }
         primary_dep = task["primary-dependency"]
-        copy_of_attributes = primary_dep.attributes.copy()
-        task.setdefault("attributes", {}).update(copy_of_attributes)
+        attributes = primary_dep.attributes.copy()
+        attributes.update(task.get("attributes", {}))
+        task["attributes"] = attributes
         # run_on_tasks_for is set as an attribute later in the pipeline
-        task.setdefault("run-on-tasks-for", copy_of_attributes["run_on_tasks_for"])
+        task.setdefault("run-on-tasks-for", attributes["run_on_tasks_for"])
         task["name"] = _get_dependent_job_name_without_its_kind(primary_dep)
 
         yield task