Better get those 0 byte files off of the mirrors. Apt is stuck. http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=595691 That's the only way to get out of this mess without needing to alert users. Get rid of the zero byte files on the mirrors, push out a new apt, and hope nobody notices. You can bring back the zero byte files weeks later if you insist, but I wouldn't.