Add ignore-dependencies option

With the previous CRD changes in effect, the merge-check pipeline
became rather large since it needlessly stacked dependent (both
git-dependent and commit-dependent) changes for each change tested.
Since commit-dependencies should not affect whether a change has
a merge conflict, and git-dependencies are already taken care of,
add an option to allow independent pipelines to ignore dependencies.

We will only set this for the merge-check pipeline in OpenStack.

Change-Id: I553446374ac12aa3e3f2e4bbea7ca8fafba42294
diff --git a/tests/fixtures/layout-ignore-dependencies.yaml b/tests/fixtures/layout-ignore-dependencies.yaml
new file mode 100644
index 0000000..5c0257c
--- /dev/null
+++ b/tests/fixtures/layout-ignore-dependencies.yaml
@@ -0,0 +1,28 @@
+pipelines:
+  - name: check
+    manager: IndependentPipelineManager
+    ignore-dependencies: true
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
+projects:
+  - name: org/project1
+    check:
+      - project1-merge:
+        - project1-test1
+        - project1-test2
+        - project1-project2-integration
+
+  - name: org/project2
+    check:
+      - project2-merge:
+        - project2-test1
+        - project2-test2
+        - project1-project2-integration