plugin XEP-0085: fixed chatstate blinking following 0632d96f08ad change

src/plugins/plugin_xep_0085.py

@@ -31,6 +31,7 @@ except ImportError:
     from wokkel.subprotocols import XMPPHandler
 from twisted.words.xish import domish
 from twisted.internet import reactor
+from twisted.internet import error as internet_error
 
 NS_XMPP_CLIENT = "jabber:client"
 NS_CHAT_STATES = "http://jabber.org/protocol/chatstates"
@@ -372,6 +373,10 @@ class ChatStateMachine(object):
                 client.xmlstream.send(mess_data['xml'])
 
         self.state = state
+        try:
+            self.timer.cancel()
+        except (internet_error.AlreadyCalled, AttributeError):
+            pass
 
         if transition["next_state"] and transition["delay"] > 0:
             self.timer = reactor.callLater(transition["delay"], self._onEvent, transition["next_state"])