I dunno which upgrade leads to this bug, but just so that you know, I've had just the same problem as you described in your first post. As in my case, the steps that lead me to the problem were following:I saw that account-haze was marked to be autoremoved by apt, but I didn't pay much attention to it So I had it for about a week. No upgrades were done to any parts of conversation-related software. Then at wednesday morning I was unable to login into ICQ and found out that haze was removed from the system. I reinstalled haze, but it did not help. Then I kept reinstalling various packages until one guy from our russian forum told me to disable repos.
sudo gainroot apt-get --purge remove libpurple0 apt-get autoremove
echo libpurple0 hold | dpkg --set-selections echo telepathy-haze hold | dpkg --set-selections
sudo gainroot apt-get update apt-get upgrade