Seen in my installer syslog:

Mar  9 20:58:30 in-target: Checking for services that may need to be restarted...
Mar  9 20:58:30 in-target: Checking init scripts...
Mar  9 20:58:31 in-target: Use of uninitialized value $template in exists at /usr/share/perl5/Debconf/Template.pm line 81, <GEN2> line 850.
Mar  9 20:58:31 in-target: Use of uninitialized value $item in exists at /usr/share/perl5/Debconf/DbDriver/Cache.pm line 39, <GEN2> line 850.
Mar  9 20:58:31 in-target: Use of uninitialized value $item in exists at /usr/share/perl5/Debconf/DbDriver/Cache.pm line 39, <GEN2> line 850.
Mar  9 20:59:10 in-target:
Mar  9 20:59:10 in-target: Restarting services possibly affected by the upgrade:
Mar  9 20:59:10 in-target:   cron: stopping...
Mar  9 20:59:11 in-target: starting...
Mar  9 20:59:11 in-target: done.

This was when pkgsel ran a aptitude upgrade, and libc6 was asking about
restarting daemons, with the question proxied to cdebconf via the passthrough
frontend. (I did see the question.)