This sounds like something that should be reported upstream. Particularly if you know how to reproduce it. Has it been?
No, largely because I can't reproduce it at all. It's happened maybe 4-5 times in the past 2 years or so. All that I see is that my end looks good yet the master end seems not to be dispatching jobs (it never shows an explicit disconnect for my slave though).
It's not really reproducible. I think it sometimes happens when I restart the master; sometimes, some clients fail to reconnect (properly).
It's easy to set up if not, the BuildSlave initializer accepts a list of email addresses that will be notified when that slave goes offline, notify_on_missing:
http://buildbot.net/apidocs/buildbot.buildslave.AbstractBuildSlave- class.html#__init__
I tried that out a couple of weeks ago, but never received any email. I didn't have the time to look into this further since. Regards, Martin