Buildbot/SchedulerDBBugs

• Events appear blank on the waterfall, like this: http://grab.by/1g0O
• Slaves sometimes get stuck. twistd.log message from a connect attempt:

2009-12-17 13:28:48-0800 [Broker,5,10.2.71.105] duplicate slave moz2-linux-slave03 replacing old one
2009-12-17 13:28:48-0800 [Broker,5,10.2.71.105] old slave was connected from IPv4Address(TCP, '10.2.71.105', 54620)
2009-12-17 13:28:48-0800 [Broker,5,10.2.71.105] new slave is from IPv4Address(TCP, '10.2.71.105', 54623)
2009-12-17 13:28:48-0800 [Broker,5,10.2.71.105] disconnecting old slave moz2-linux-slave03 now
2009-12-17 13:28:48-0800 [Broker,5,10.2.71.105] waiting for slave to finish disconnecting