py2/py3: return None in ZSQLBrain._aq_dynamic() if getObject() because of missing path.

in Python 2, _aq_dynamic() returns None without try..except but it raises ValueError in Python 3.

(python 2)
> /SR/parts/erp5/product/ZSQLCatalog/Extensions/zsqlbrain.py(31)_aq_dynamic()
 31  ->   def _aq_dynamic(self, name):
 32         """Acquire an attribute from a real object.
 33         """
 34         if name.startswith('__') :
 35           return None
 36         return getattr(self.getObject(), name, None)
((Pdb)) getattr(self.getObject(), name, None)
*** ValueError: Unable to getObject from ZSQLBrain if ZSQL Method does not retrieve the `path` column from catalog table.
((Pdb)) r
--Return--
> /SR/parts/erp5/product/ZSQLCatalog/Extensions/zsqlbrain.py(36)_aq_dynamic()->None # <-- !!!

product/ZSQLCatalog/Extensions/zsqlbrain.py

@@ -33,7 +33,11 @@ class ZSQLBrain(Acquisition.Implicit):
     """
     if name.startswith('__') :
       return None
-    return getattr(self.getObject(), name, None)
+    try:
+      obj = self.getObject()
+    except ValueError:
+      return None
+    return getattr(obj, name, None)
 
   def getURL(self):
     return self.path