Speed up BT upgrade by exporting temporarily to RAM instead of temporary files

Although this also fixes "too many files" error, the way to upgrade some kinds
of objects should be reviewed in order to avoid such export/import.

product/ERP5/Document/BusinessTemplate.py

@@ -845,30 +845,27 @@ class ObjectTemplateItem(BaseTemplateItem):
     """
       Backup the object in portal trash if necessery and return its subobjects
     """
-    subobjects_dict = {}
+    p = self.getPortalObject()
     if trashbin is None: # must return subobjects
-      object_path = container_path + [object_id]
-      obj = self.unrestrictedTraverse(object_path)
-      for subobject_id in list(obj.objectIds()):
-        subobject_path = object_path + [subobject_id]
-        subobject = self.unrestrictedTraverse(subobject_path)
-        subobject_copy = subobject._p_jar.exportFile(subobject._p_oid)
-        subobjects_dict[subobject_id] = subobject_copy
-      return subobjects_dict
+      subobject_dict = {}
+      obj = p.unrestrictedTraverse(container_path)[object_id]
+      for subobject_id in obj.objectIds():
+        subobject = obj[subobject_id]
+        subobject_dict[subobject_id] = subobject._p_jar.exportFile(
+            subobject._p_oid, StringIO())
+      return subobject_dict
     # XXX btsave is for backward compatibility
     if action in ('backup', 'btsave', 'save_and_remove',):
-      subobjects_dict = self.portal_trash.backupObject(trashbin, 
-                                                container_path, object_id, 
-                                                save=1, **kw)
+      save = 1
     elif action in ('install', 'remove'):
-      subobjects_dict = self.portal_trash.backupObject(trashbin, 
-                                                container_path, object_id, 
-                                                save=0, **kw)
+      save = 0
     else:
       # As the list of available actions is not strictly defined,
       # prevent mistake if an action is not handled
       raise NotImplementedError, 'Unknown action "%s"' % action
-    return subobjects_dict
+    return p.portal_trash.backupObject(trashbin, container_path, object_id,
+                                       save=save, **kw)
+
 
   def beforeInstall(self):
     """
@@ -950,6 +947,7 @@ class ObjectTemplateItem(BaseTemplateItem):
       original_reindex_parameters = self.setSafeReindexationMode(context)
       object_key_list = self._getObjectKeyList()
       for path in object_key_list:
+        __traceback_info__ = path
         # We do not need to perform any backup because the object was
         # created during the Business Template installation
         if update_dict.get(path) == 'migrate':