Deregister timeout on broken

When broken for whatever reason, we do not want timeout handling
to continue trying to heal the session.  Notably bad when login fails
and a _relog is triggered continually.

Change-Id: Id342a7fc1274fe95483f2e5392b04f86d23c2b1a

pyghmi/ipmi/private/session.py

@@ -388,6 +388,7 @@ class Session(object):
         # since our connection has failed retries
         # deregister our keepalive facility
         Session.keepalive_sessions.pop(self, None)
+        Session.waiting_sessions.pop(self, None)
         if self.logged:
             self.logged = 0  # mark session as busted
             self._customkeepalives = None