Delete storage in the order the nodes are instantiated

Otherwise if it fails before hard_input is defined, the finally clause never deletes the self.n1 storage because there's a second failure _inside_ finally

tests/unit/test_node.py

@@ -481,8 +481,8 @@ def test_storage(self):
                         ):
                             hard_input.save()
                 finally:
-                    hard_input.delete_storage(backend)
                     self.n1.delete_storage(backend)
+                    hard_input.delete_storage(backend)
 
     def test_checkpoint(self):
         for backend in Node.allowed_backends():