После обновления до Ubuntu 14.04.3 LTS MOTD всегда сообщает, что можно обновить 0 новых пакетов.

Я не эксперт по серверам и поэтому испытываю некоторые проблемы с обновлением Ubuntu. Немного истории: моя капля Digital Ocean работала под управлением Ubuntu 12.04 LTS, затем несколько месяцев назад я обновился до более новой HWE, чтобы продолжать получать обновления безопасности для версии 12.04. Недавно я обновил Ubuntu до 14.04 LTS. Кажется, все работает нормально, за исключением того, что я не получаю никаких уведомлений о том, что есть пакеты для обновления. После входа на мой сервер сообщение дня продолжает отображаться:

0 packages can be updated.
0 updates are security updates.

что просто не может быть правильным в течение 3 недель ...?

Бег sudo apt-get update работает без ошибок и sudo apt-get upgrade говорит 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

У меня такое ощущение что мой /etc/apt/sources.list был каким-то образом поврежден после обновления до нового ядра HWE, а затем до нового LTS. Ниже перечислены источники, перечисленные в настоящее время. Кто-нибудь видит проблемы с этим списком? Любой совет будет принят во внимание.

$ cat /etc/apt/sources.list

#

# deb cdrom:[Ubuntu-Server 12.04.3 LTS _Precise Pangolin_ - Release i386 (20130820.2)]/ precise main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
## DigitalOcean mirrors for blazing speed!
deb http://mirrors.digitalocean.com/ubuntu/ trusty main restricted
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty main restricted
# deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted

## Major bug fix updates produced after the final release of the
## distribution.
## DigitalOcean mirrors for blazing speed!
deb http://mirrors.digitalocean.com/ubuntu/ trusty-updates main restricted
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-updates main restricted
# deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
## DigitalOcean mirrors for blazing speed!
deb http://mirrors.digitalocean.com/ubuntu/ trusty universe
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty universe
deb http://mirrors.digitalocean.com/ubuntu/ trusty-updates universe
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-updates universe
# deb http://us.archive.ubuntu.com/ubuntu/ precise universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise universe
# deb http://us.archive.ubuntu.com/ubuntu/ precise-updates universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
## DigitalOcean mirrors for blazing speed!
deb http://mirrors.digitalocean.com/ubuntu/ trusty multiverse
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty multiverse
deb http://mirrors.digitalocean.com/ubuntu/ trusty-updates multiverse
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-updates multiverse
# deb http://us.archive.ubuntu.com/ubuntu/ precise multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise multiverse
# deb http://us.archive.ubuntu.com/ubuntu/ precise-updates multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
## DigitalOcean mirrors for blazing speed!
deb http://mirrors.digitalocean.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-backports main restricted universe multiverse
# deb http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse

## DigitalOcean mirrors for blazing speed!
deb http://mirrors.digitalocean.com/ubuntu/ trusty-security main restricted
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-security main restricted
deb http://mirrors.digitalocean.com/ubuntu/ trusty-security universe
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-security universe
deb http://mirrors.digitalocean.com/ubuntu/ trusty-security multiverse
deb-src http://mirrors.digitalocean.com/ubuntu/ trusty-security multiverse
# deb http://security.ubuntu.com/ubuntu precise-security main restricted
# deb-src http://security.ubuntu.com/ubuntu precise-security main restricted
# deb http://security.ubuntu.com/ubuntu precise-security universe
# deb-src http://security.ubuntu.com/ubuntu precise-security universe
# deb http://security.ubuntu.com/ubuntu precise-security multiverse
# deb-src http://security.ubuntu.com/ubuntu precise-security multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu precise partner
# deb-src http://archive.canonical.com/ubuntu precise partner

## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu precise main
# deb-src http://extras.ubuntu.com/ubuntu precise main