Fix debug message output

Author: pglombardo

instana/fsm.py

@@ -140,7 +140,7 @@ def schedule_retry(self, fun, e, name):
         self.timer.daemon = True
         self.timer.name = name
         self.timer.start()
-        l.debug('Threadlist: %s', str(t.enumerate()))
+        l.debug('Threadlist: ', str(t.enumerate()))
 
     def test_agent(self, e):
         l.debug("testing communication with the agent")