When using a AbstractLatentBuildSlave with build_wait_timeout >0, I have this tracback when the slave is disconnected when the build_wait_timer fired: 

	Traceback (most recent call last):
	  File "/home/xavierd/Projects/myGitHub/buildbot-work/sandbox/local/lib/python2.7/site-packages/twisted/spread/pb.py", line 1341, in maybeLogout
	    fn()
	  File "/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/pbmanager.py", line 177, in <lambda>
	    return (pb.IPerspective, persp, lambda: persp.detached(mind))
	  File "/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/buildslave/protocols/pb.py", line 104, in detached
	    self.notifyDisconnected()
	  File "/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/buildslave/protocols/base.py", line 43, in notifyDisconnected
	    self._disconnectSubs.deliver()
	--- <exception caught here> ---
	  File "/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/util/subscription.py", line 37, in deliver
	    sub.callback(*args, **kwargs)
	exceptions.TypeError: _disconnected() takes exactly 1 argument (0 given)


sub.callback is: 

        # notifyOnDisconnect runs the callback with one argument, the
        # RemoteReference being disconnected.
        def _disconnected(rref):
            eventually(d.callback, None)

my fix is: 
        def _disconnected():
            eventually(d.callback, None)