GC: Add check for nil interface

pkg/registry/rbac/helpers.go

@@ -17,6 +17,8 @@ limitations under the License.
 package rbac
 
 import (
+	"reflect"
+
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/conversion"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -25,6 +27,10 @@ import (
 // IsOnlyMutatingGCFields checks finalizers and ownerrefs which GC manipulates
 // and indicates that only those fields are changing
 func IsOnlyMutatingGCFields(obj, old runtime.Object, equalities conversion.Equalities) bool {
+	if old == nil || reflect.ValueOf(old).IsNil() {
+		return false
+	}
+
 	// make a copy of the newObj so that we can stomp for comparison
 	copied := obj.DeepCopyObject()
 	copiedMeta, err := meta.Accessor(copied)