I discovered this morning when upgrading my sid box, that runit-run and 
socklog-run both failed in interesting ways.

Runit-run replaces the getty links in /var/service with new ones 
in /etc/sv.  If you're running the upgrade from a getty, the getty will 
die when its service dir link is removed to be replaced, leaving 
non-functional services.  I was able to get in via ssh and fix the links 
so that the getty's worked, and also tested not-fixing them and letting 
dpkg --configure -a finish the job.  Both worked.  

The next problem is less of a show-stopper, but still needs to be paid 
attention to.  Socklog-run upgrade similar replaces the 
old /etc/socklog-? links with /etc/sv/socklog-?.  but it doesn't remove 
the old symlinks in /var/service first, and so ln fails because the 
target already exists.  Removing the old links allows the postinst 
portion of the deb installation to finish.

I'm not sure there are good ways to get around this on an upgrade of these 
packages, so I'm uncertain if I should try to file a bug report.  Any 
thoughts?