upgrading docker

a.md

# docker version
Client version: 0.6.4
Go version (client): go1.1.2
Git commit (client): 2f74b1c
Server version: 0.6.4
Git commit (server): 2f74b1c
Go version (server): go1.1.2
Last stable version: 0.6.5, please update docker

# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
  lxc-docker
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.

You can upgrade by simply running sudo apt-get install lxc-docker

That leaves unanswered the question of why it was held back. Anyone know?

I found this post via Google search and since no one else has answered, I think that the reason is that it has something to do with the way docker is released as a new version of itself. Sort of a guess by looking at the availability of all the versions of docker on my system.

The same problem just occurred again upgrading from Docker lxc-docker-1.4.1 to 1.5.0 (on Ubuntu 14.0.4 for me).

The following packages have been kept back:
  lxc-docker
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.

Forcing sudo apt-get install lxc-docker fixed the problem:

The following extra packages will be installed:
  lxc-docker-1.5.0
The following packages will be REMOVED:
  lxc-docker-1.4.1
The following NEW packages will be installed:
  lxc-docker-1.5.0
The following packages will be upgraded:
  lxc-docker
1 upgraded, 1 newly installed, 1 to remove and 0 not upgraded.