fix: added back deepcopy

Author: satra

nipype/interfaces/base.py

@@ -512,7 +512,23 @@ def __setstate__(self, state):
         super(BaseTraitedSpec, self).__setstate__(state)
 
 class DynamicTraitedSpec(BaseTraitedSpec):
-    pass
+    """ A subclass to handle dynamic traits
+
+    This class is a workaround for add_traits and clone_traits not
+    functioning well together.
+    """
+    def __deepcopy__(self, memo):
+        """ bug in deepcopy for HasTraits results in weird cloning behavior for
+        added traits
+        """
+        id_self = id(self)
+        if id_self in memo:
+            return memo[id_self]
+        dup_dict = deepcopy(self.__getstate__(), memo)
+        dup = self.clone_traits(memo=memo)
+        dup.__setstate__(dup_dict)
+        return dup
+
 
 class TraitedSpec(BaseTraitedSpec):
     """ Create a subclass with strict traits.