Comment 2 for bug 1304657

Ok, on a longtime trusty-amd64 livecd install, I confirmed that these files didn't exist. I updated to newest trusty (it was slightly out of date) and they still didn't exist. I then attached the iso to the VM, booted, had the VM mount in Unity, then did:
$ sudo apt-cdrom --cdrom '/media/jamie/Ubuntu 14.04 LTS amd64' --no-auto-detect --no-mount add
$ sudo apt-get update
$ ls -l /var/lib/apt/lists/ |grep 'rw-rw-rw'
-rw-rw-rw- 1 root root 29759 Apr 8 16:25 Ubuntu%2014.04%20LTS%20%5fTrusty%20Tahr%5f%20-%20Daily%20amd64%20(20140407)_dists_trusty_main_binary-amd64_Packages
-rw-rw-rw- 1 root root 0 Apr 8 16:25 Ubuntu%2014.04%20LTS%20%5fTrusty%20Tahr%5f%20-%20Daily%20amd64%20(20140407)_dists_trusty_main_binary-i386_Packages
-rw-rw-rw- 1 root root 1199 Apr 8 16:25 Ubuntu%2014.04%20LTS%20%5fTrusty%20Tahr%5f%20-%20Daily%20amd64%20(20140407)_dists_trusty_restricted_binary-amd64_Packages
-rw-rw-rw- 1 root root 0 Apr 8 16:25 Ubuntu%2014.04%20LTS%20%5fTrusty%20Tahr%5f%20-%20Daily%20amd64%20(20140407)_dists_trusty_restricted_binary-i386_Packages

I then commented out the entry in /etc/apt/sources.list, ran apt-get update and the above files disappeared.