Comment 5 for bug 113424

Depends on how you look at it. Here is a plausible account of what might have happened .
Apt-get update starts to update then runs out of Cache-Limit space which corrupts some files in the lists folder.
Next time you run apt-get it goes bang with a core dump error.
Clearing out the lists folder stops apt going bang but revels the Cache-Limit problem.
It's a bit of a chicken and egg problem.
I have to say since I made the above changes I have not had a problem.
Nice to know you have take an interest.
Regards
Ray