rules: fix test for device equality

docs/rules.md

@@ -116,8 +116,9 @@ or the window's Window manager class or instance name starts with their string a
 
 `Device` conditions are true if a particular device originated the notification.
 `Active` conditions are true if a particular device is active.
-`Device` and `Active` conditions take one argument, which is the Serial number or Unit ID of a device,
+`Device` and `Active` conditions take one argument, which is the serial number or unit ID of a device,
 as shown in Solaar's detail pane.
+Some older devices do not have a useful serial number or unit ID and so cannot be tested for by these conditions.
 
 `Host' conditions are true if the computers hostname starts with the condition's argument.
 

lib/logitech_receiver/diversion.py

@@ -1051,8 +1051,7 @@ class Device(Condition):
     def evaluate(self, feature, notification, device, status, last_result):
         if _log.isEnabledFor(_DEBUG):
             _log.debug('evaluate condition: %s', self)
-        dev = _Device.find(self.devID)
-        return device == dev
+        return device.unitId == self.devID or device.serial == self.devID
 
     def data(self):
         return {'Device': self.devID}