prevent RFB clients from locking the session and preventing other cli…

…ents from connecting

git-svn-id: https://xpra.org/svn/Xpra/trunk@19461 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/server/rfb/rfb_source.py

@@ -23,6 +23,7 @@ def __init__(self, protocol, desktop, share=False):
         self.counter = 0
         self.share = share
         self.uuid = "todo: use protocol?"
+        self.lock = False
 
     def get_info(self):
         return {