Keep $node->is_new flag after firing "Workflow state has changed" event

The problem arises when you have set up several events triggered by the same hook. In my case the event "Workflow state has changed" and "After saving new content" are invoked in hook_nodeapi($op = 'update'). Due to the default module weight the workflow event is fired first, modifies the saves the node. The second event has the condition "Node is new" which of course doesn't apply any more and leads to unexpected system behavior.

So let's keep the $node->is_new flag, so that subsequent rules can interpret the node state properly.