Don't output complex items in the summary line

When iterating over complex objects, printing them out in the task
summary line is very noisy and hard to follow.

Change-Id: I4ae748f167ee03ba97a4bcbf2417dae0271e24a5
diff --git a/playbooks/zuul-stream/fixtures/test-stream.yaml b/playbooks/zuul-stream/fixtures/test-stream.yaml
index 5bffc16..29bbf47 100644
--- a/playbooks/zuul-stream/fixtures/test-stream.yaml
+++ b/playbooks/zuul-stream/fixtures/test-stream.yaml
@@ -20,6 +20,13 @@
         - item2
         - item3
 
+    - name: Loop with complex items
+      command: "echo {{ item.name }}"
+      with_items:
+        - name: complex1
+        - name: complex2
+        - name: complex3
+
     - name: Run a shell task with an ansible python exception
       command: echo foo
       args: