Comment 3 for bug 1259191

 ls -l security.conf
-rw------- 1 apt-cacher-ng apt-cacher-ng 401 Mar 20 2008 security.conf

I did comment out the Remap-gentoo linei n acng.conf (kind of odd that this would be enabled on an Ubuntu system?)

% bzr diff acng.conf
=== modified file 'apt-cacher-ng/acng.conf'
--- apt-cacher-ng/acng.conf 2013-12-09 14:14:13 +0000
+++ apt-cacher-ng/acng.conf 2013-12-09 14:52:11 +0000
@@ -44,7 +44,7 @@
 Remap-fedora: file:fedora_mirrors # Fedora Linux
 Remap-epel: file:epel_mirrors # Fedora EPEL
 Remap-slrep: file:sl_mirrors # Scientific Linux
-Remap-gentoo: file:gentoo_mirrors.gz /gentoo ; file:backends_gentoo # Gentoo Archives
+#Remap-gentoo: file:gentoo_mirrors.gz /gentoo ; file:backends_gentoo # Gentoo Archives

 # This is usually not needed for security.debian.org because it's always the
 # same DNS hostname. However, it might be enabled in order to use hooks,