insolvency_proceeding: repair InsolvencyProceeding XML

I don't know how it was exported, but this object does not install:

     File "/parts/erp5/product/ERP5/Document/BusinessTemplate.py", line 4141, in install
       return ObjectTemplateItem.install(self, context, **kw)
     File "/parts/erp5/product/ERP5/Document/BusinessTemplate.py", line 1422, in install
       container._setObject(object_id, obj)
     File "/parts/erp5/product/ERP5Type/Base.py", line 253, in __call__
       result = self.__dict__['_m'](instance, *args, **kw)
     File "/parts/erp5/product/ERP5Type/Core/Folder.py", line 1055, in _setObject
       return folder._setObject(self, *args, **kw)
     File "/eggs/Products.BTreeFolder2-2.13.5-py2.7.egg/Products/BTreeFolder2/BTreeFolder2.py", line 443, in _setObject
       self._setOb(id, ob)
     File "/parts/erp5/product/ERP5Type/Core/Folder.py", line 970, in _setOb
       return folder._setOb(self, id, object)
     File "/eggs/Products.BTreeFolder2-2.13.5-py2.7.egg/Products/BTreeFolder2/BTreeFolder2.py", line 256, in _setOb
       ids = mti.get(meta_type, None)
   AttributeError: 'NoneType' object has no attribute 'get'

bt5/erp5_insolvency_proceeding/PropertySheetTemplateItem/portal_property_sheets/InsolvencyProceeding.xml

@@ -13,11 +13,17 @@
             </value>
         </item>
         <item>
-            <key> <string>_tree</string> </key>
+            <key> <string>_mt_index</string> </key>
             <value>
               <persistent> <string encoding="base64">AAAAAAAAAAM=</string> </persistent>
             </value>
         </item>
+        <item>
+            <key> <string>_tree</string> </key>
+            <value>
+              <persistent> <string encoding="base64">AAAAAAAAAAQ=</string> </persistent>
+            </value>
+        </item>
         <item>
             <key> <string>description</string> </key>
             <value>
@@ -49,4 +55,12 @@
       <none/>
     </pickle>
   </record>
+  <record id="4" aka="AAAAAAAAAAQ=">
+    <pickle>
+      <global name="OOBTree" module="BTrees.OOBTree"/>
+    </pickle>
+    <pickle>
+      <none/>
+    </pickle>
+  </record>
 </ZopeData>