[#XX] client: Allow empty patches

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

client/object_patch.go

@@ -176,10 +176,10 @@ func (x *objectPatcher) PatchPayload(_ context.Context, rng *object.Range, paylo
 		}
 		if n == 0 {
 			if patchIter == 0 {
-				if rng.GetLength() == 0 {
+				// if rng.GetLength() == 0 {
-					x.err = errors.New("zero-length empty payload patch can't be applied")
+				// 	x.err = errors.New("zero-length empty payload patch can't be applied")
-					return false
+				// 	return false
-				}
+				// }
 				if !x.patch(&object.Patch{
 					Address: x.addr,
 					PayloadPatch: &object.PayloadPatch{