remove parent pointer while exporting

src/OFS/ObjectManager.py

@@ -22,6 +22,7 @@ import marshal
 import os
 import re
 import sys
+import transaction
 
 from AccessControl import ClassSecurityInfo
 from AccessControl.class_init import InitializeClass
@@ -584,10 +585,24 @@ class ObjectManager(CopyContainer,
 
         cfg = getConfiguration()
         f = os.path.join(cfg.clienthome, '%s.%s' % (id, suffix))
-        if toxml:
-            exportXML(ob._p_jar, ob._p_oid, f)
-        else:
-            ob._p_jar.exportFile(ob._p_oid, f)
+
+        ob = aq_base(ob)
+        parent = getattr(ob, '__parent__', _marker)
+        if parent is not _marker:
+            sp = transaction.savepoint(True)
+            del ob.__parent__
+            # create a savepoint so that the export includes the version
+            # without a __parent__ pointer
+            transaction.savepoint(True)
+        try:
+            if toxml:
+                exportXML(ob._p_jar, ob._p_oid, f)
+            else:
+                ob._p_jar.exportFile(ob._p_oid, f)
+        finally:
+            if parent is not _marker:
+                # roll back so that we don't actually remove the __parent__
+                sp.rollback()
 
         if REQUEST is not None:
             return self.manage_main(self, REQUEST,