Save the bookmarks after changing the storage method

also fix a check that would make the handler never trigger…

src/core/core.py

@@ -355,9 +355,10 @@ class Core(object):
         """
         Called when the use_bookmarks_method option changes
         """
-        if 'value' not in ('pep', 'privatexml'):
+        if value not in ('pep', 'privatexml'):
             return
         self.bookmarks.preferred = value
+        self.bookmarks.save(self.xmpp, core=self)
 
     def on_gaps_config_change(self, option, value):
         """