Don't copy _paths when cloning Cell or Material

openmc/cell.py

@@ -527,8 +527,16 @@ class Cell(object):
 
         # If no nemoize'd clone exists, instantiate one
         if self not in memo:
+            # Temporarily remove paths
+            paths = self.paths
+            self._paths = None
+
             clone = deepcopy(self)
             clone.id = None
+
+            # Restore paths on original instance
+            self._paths = paths
+
             if self.region is not None:
                 clone.region = self.region.clone(memo)
             if self.fill is not None:
@@ -542,7 +550,7 @@ class Cell(object):
             memo[self] = clone
 
         return memo[self]
-    
+
     def create_xml_subelement(self, xml_element):
         element = ET.Element("cell")
         element.set("id", str(self.id))

openmc/material.py

@@ -820,9 +820,18 @@ class Material(object):
 
         # If no nemoize'd clone exists, instantiate one
         if self not in memo:
+            # Temporarily remove paths -- this is done so that when the clone is
+            # made, it doesn't create a copy of the paths (which are specific to
+            # an instance)
+            paths = self.paths
+            self._paths = None
+
             clone = deepcopy(self)
             clone.id = None
 
+            # Restore paths on original instance
+            self._paths = paths
+
             # Memoize the clone
             memo[self] = clone