Use kustomization namespace for empty dependency source namespace

Kustomize controller uses the namespace of the kustomization resource
if the sourceRef is empty. However, this policy doesn't applied to
dependencies. This can be problematic if the same named `Sources`
without explicit namespace is in different namespace.

This commit fixes this issue by using kustomization's namespace when
checking dependencies if the namespace in sourceRef is empty.

Signed-off-by: Sunghoon Kang <me@hoon.dev>

internal/controller/kustomization_controller.go

@@ -483,8 +483,17 @@ func (r *KustomizationReconciler) checkDependencies(ctx context.Context,
 			return fmt.Errorf("dependency '%s' is not ready", dName)
 		}
 
+		srcNamespace := k.Spec.SourceRef.Namespace
+		if srcNamespace == "" {
+			srcNamespace = k.GetNamespace()
+		}
+		dSrcNamespace := obj.Spec.SourceRef.Namespace
+		if dSrcNamespace == "" {
+			dSrcNamespace = obj.GetNamespace()
+		}
+
 		if k.Spec.SourceRef.Name == obj.Spec.SourceRef.Name &&
-			k.Spec.SourceRef.Namespace == obj.Spec.SourceRef.Namespace &&
+			srcNamespace == dSrcNamespace &&
 			k.Spec.SourceRef.Kind == obj.Spec.SourceRef.Kind &&
 			!source.GetArtifact().HasRevision(k.Status.LastAppliedRevision) {
 			return fmt.Errorf("dependency '%s' revision is not up to date", dName)