Avoid calling new.unlock() in __deepcopy__()

since the new object's properties aren't necessarily deepcopied yet...

masque/repetition.py

@@ -116,7 +116,8 @@ class Grid(LockableImpl, Repetition, metaclass=AutoSlots):
 
     def __deepcopy__(self, memo: Dict = None) -> 'Grid':
         memo = {} if memo is None else memo
-        new = copy.copy(self).unlock()
+        new = copy.copy(self)
+        LocakbleImpl.unlock(new)
         new.locked = self.locked
         return new