Nasty bug, this one, took a long time to debug.
Fix warning from scheduler saying "KIO::SchedulerPrivate::slotSlaveDied: Scheduler: BUG!! Slave KIO::Slave(0x6ee820) / 3788 died, but is NOT in slaveList!!!" simply because deref() used to delete the slave immediately in kde3, and delayed in kde4, so it would keep processing the replies sent by the slave.