[kupfer] plugin.notes: Fix attribute_error when deleting monitor_token

[Ulrik Sverdrup <usverdrup src gnome org>]

commit b95af696e147fab9baf5502832b71d14e685f468
Author: Ulrik Sverdrup <ulrik sverdrup gmail com>
Date:   Mon Aug 31 20:43:07 2009 +0200

    plugin.notes: Fix attribute_error when deleting monitor_token

 kupfer/plugin/notes.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/kupfer/plugin/notes.py b/kupfer/plugin/notes.py
index 1fa0ca5..3c71ff2 100644
--- a/kupfer/plugin/notes.py
+++ b/kupfer/plugin/notes.py
@@ -148,7 +148,7 @@ class NotesSource (AppLeafContentMixin, Source, PicklingHelperMixin,
 		self.monitor_token = self.monitor_directories(*dirs)
 
 	def pickle_prepare(self):
-		del self.monitor_token
+		self.monitor_token = None
 
 	def _update_cache(self, notes):
 		try: