Comment 2 for bug 1425662

apt 1.1~exp4 fixes this issue (see also debbug #762898) in git commit 43acd01979039b248cb7f033b82e36d778d0ebec, so try that version then it appears in Ubuntu. Using of the root cache (if available) is at least supposed to happen in that version as well (but also in the version you have… I will give it a spin later… can't be hard,right? ;) )