oc: rolling back to the same dc version should be a no-op

pkg/deploy/registry/rollback/rest.go

@@ -64,6 +64,8 @@ func (r *REST) Create(ctx kapi.Context, obj runtime.Object) (runtime.Object, err
 		return nil, newInvalidError(rollback, "cannot rollback an undeployed config")
 	case 1:
 		return nil, newInvalidError(rollback, fmt.Sprintf("no previous deployment exists for %q", deployutil.LabelForDeploymentConfig(from)))
+	case rollback.Spec.Revision:
+		return nil, newInvalidError(rollback, fmt.Sprintf("version %d is already the latest", rollback.Spec.Revision))
 	}
 
 	revision := from.Status.LatestVersion - 1

pkg/deploy/registry/rollback/rest_test.go

@@ -86,6 +86,27 @@ func TestCreateOk(t *testing.T) {
 	}
 }
 
+func TestCreateRollbackToLatest(t *testing.T) {
+	oc := &testclient.Fake{}
+	oc.AddReactor("get", "deploymentconfigs", func(action core.Action) (handled bool, ret runtime.Object, err error) {
+		return true, deploytest.OkDeploymentConfig(2), nil
+	})
+
+	_, err := NewREST(oc, &fake.Clientset{}, codec).Create(kapi.NewDefaultContext(), &deployapi.DeploymentConfigRollback{
+		Name: "config",
+		Spec: deployapi.DeploymentConfigRollbackSpec{
+			Revision: 2,
+		},
+	})
+
+	if err == nil {
+		t.Errorf("expected an error when rolling back to the existing deployed revision")
+	}
+	if err != nil && !strings.Contains(err.Error(), "version 2 is already the latest") {
+		t.Errorf("unexpected error received: %v", err)
+	}
+}
+
 func TestCreateGeneratorError(t *testing.T) {
 	oc := &testclient.Fake{}
 	oc.AddReactor("get", "deploymentconfigs", func(action core.Action) (handled bool, ret runtime.Object, err error) {

test/cmd/deployments.sh

@@ -111,6 +111,8 @@ os::cmd::expect_failure 'oc rollback database -o yaml'
 os::cmd::expect_success 'oc set image dc/database ruby-helloworld-database=foo --source=docker'
 # wait for the new deployment
 os::cmd::try_until_success 'oc rollout history dc/database --revision=2'
+# rolling back to the same revision should fail
+os::cmd::expect_failure 'oc rollback dc/database --to-version=2'
 # undo --dry-run should report the original image
 os::cmd::expect_success_and_text 'oc rollout undo dc/database --dry-run' 'mysql-57-centos7'
 echo "rollback: ok"