Fix python error when using the DaVinci configurable with the Upgrade DataType...

Fix python error when using the DaVinci configurable with the Upgrade DataType and no specific list of detectors.

Phys/DaVinci/python/DaVinci/Configuration.py

@@ -596,7 +596,7 @@ class DaVinci(LHCbConfigurableUser) :
                 log.info ('Define CondDB( Upgrade = True ) ')
                 _db.Upgrade = True
             if  not self.isPropertySet('Detectors') or not self.getProp('Detectors') :
-                upgrade_only_dets = [ d for d in __known_upgrade_detectors__ if d not in __known_default_detectors]
+                upgrade_only_dets = [ d for d in self.__known_upgrade_detectors__ if d not in self.__known_default_detectors]
                 log.warning("It is suspicious that the list of ``Detectors'' is not specified though ``DataType=Upgrade'' ...")
                 log.warning("Sure that none of the upgrade-only detectors %s are to be specified via ``Detectors''?" % upgrade_only_dets )
             from Configurables import SimConf