Speed configuration building

Together, these changes build an OpenStack-sized configuration in
8% of the time it currently takes.

Change-Id: I85f538a7ebdb82724559203e2c5d5380c07f07e7
diff --git a/tests/fixtures/layouts/job-vars.yaml b/tests/fixtures/layouts/job-vars.yaml
new file mode 100644
index 0000000..22fc5c2
--- /dev/null
+++ b/tests/fixtures/layouts/job-vars.yaml
@@ -0,0 +1,75 @@
+- pipeline:
+    name: check
+    manager: independent
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        Verified: 1
+    failure:
+      gerrit:
+        Verified: -1
+
+- job:
+    name: base
+    parent: null
+
+- job:
+    name: parentjob
+    parent: base
+    required-projects:
+      - org/project0
+    vars:
+      override: 0
+      child1override: 0
+      parent: 0
+
+- job:
+    name: child1
+    parent: parentjob
+    required-projects:
+      - org/project1
+    vars:
+      override: 1
+      child1override: 1
+      child1: 1
+
+- job:
+    name: child2
+    parent: parentjob
+    required-projects:
+      - org/project2
+    vars:
+      override: 2
+      child2: 2
+
+- job:
+    name: child3
+    parent: parentjob
+
+- project:
+    name: org/project
+    check:
+      jobs:
+        - parentjob
+        - child1
+        - child2
+        - child3:
+            required-projects:
+              - org/project3
+            vars:
+              override: 3
+              child3: 3
+
+- project:
+    name: org/project0
+
+- project:
+    name: org/project1
+
+- project:
+    name: org/project2
+
+- project:
+    name: org/project3