Add a test for a broken config on startup

We currently log an exception and then exit, requiring operator
intervention.

Change-Id: I39f7a0fea7c59776d929718fb4116e62d23d25cc
diff --git a/tests/fixtures/config/broken/git/common-config/zuul.yaml b/tests/fixtures/config/broken/git/common-config/zuul.yaml
new file mode 100644
index 0000000..6abb87f
--- /dev/null
+++ b/tests/fixtures/config/broken/git/common-config/zuul.yaml
@@ -0,0 +1,17 @@
+- pipeline:
+    name: check
+    manager: independent
+    source:
+      gerrit
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
+- project:
+error: true
diff --git a/tests/fixtures/config/broken/main.yaml b/tests/fixtures/config/broken/main.yaml
new file mode 100644
index 0000000..a22ed5c
--- /dev/null
+++ b/tests/fixtures/config/broken/main.yaml
@@ -0,0 +1,6 @@
+- tenant:
+    name: tenant-one
+    source:
+      gerrit:
+        config-repos:
+          - common-config