getModificationDate: sometimes _p_serial cannot be used for DateTime (...

getModificationDate: sometimes _p_serial cannot be used for DateTime ( TimeError: The time -2208988800.000000 is beyond the range of this Python implementation. )

product/ERP5Type/Base.py

@@ -3133,7 +3133,10 @@ class Base( CopyContainer,
         # Return a copy of history time, to prevent modification
         return DateTime(max_date)
     if self._p_serial:
-      return DateTime(TimeStamp(self._p_serial).timeTime())
+      try:
+        return DateTime(TimeStamp(self._p_serial).timeTime())
+      except DateTime.TimeError:
+        return None
 
   # Layout management
   security.declareProtected(Permissions.AccessContentsInformation, 'getApplicableLayout')