Comment 16 for bug 606491

I got this too, and after reading the comments, I think it's both (ana)cron and apt doing something wrong.

This may also be a security bug, since apt will keep a lock and automatic updates (which is configured on my system) may not be running due to a stuck apt process. The apt process is really dead, but the run-parts daily process is stuck. killing that took care of the stuck apt child process.