From 81fcd19ec60400658dea389cb80fbe4a6eefeef4 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Fri, 26 May 2017 07:52:39 -0500
Subject: [PATCH] Don't copy _paths when cloning Cell or Material

---
 openmc/cell.py     | 10 +++++++++-
 openmc/material.py |  9 +++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/openmc/cell.py b/openmc/cell.py
index 4496062f7..a06270201 100644
--- a/openmc/cell.py
+++ b/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))
diff --git a/openmc/material.py b/openmc/material.py
index 202f46c1b..f7ca9c9fd 100644
--- a/openmc/material.py
+++ b/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