1 files changed, 11 insertions, 1 deletions
diff --git a/taskcluster/gecko_taskgraph/transforms/test/variant.py b/taskcluster/gecko_taskgraph/transforms/test/variant.py
index bda91b2f25..6ee6c429f0 100644
--- a/taskcluster/gecko_taskgraph/transforms/test/variant.py
+++ b/taskcluster/gecko_taskgraph/transforms/test/variant.py
@@ -78,6 +78,14 @@ def split_variants(config, tasks):
             remaining_variants.append(name)
         return remaining_variants
 
+    def replace_task_items(task_key, variant_key):
+        for item in variant_key:
+            if isinstance(variant_key[item], dict):
+                task_key[item] = replace_task_items(task_key[item], variant_key[item])
+            else:
+                task_key[item] = variant_key[item]
+        return task_key
+
     def apply_variant(variant, task):
         task["description"] = variant["description"].format(**task)
 
@@ -94,7 +102,9 @@ def split_variants(config, tasks):
         task["variant-suffix"] += suffix
 
         # Replace and/or merge the configuration.
-        task.update(variant.get("replace", {}))
+
+        # we only want to update the leaf node, the the entire top level dict
+        task = replace_task_items(task, variant.get("replace", {}))
         return merge(task, variant.get("merge", {}))
 
     expired_variants = find_expired_variants(TEST_VARIANTS)