docker upgrade wipes out docker group in /etc/group

gistfile1.sh

vagrant@precise64:~$ cat /etc/group | grep docker
docker:x:998:vagrant
vagrant@precise64:~$ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be REMOVED:
  lxc-docker-0.6.5
The following NEW packages will be installed:
  lxc-docker-0.6.6
The following packages will be upgraded:
  lxc lxc-docker procps
3 upgraded, 1 newly installed, 1 to remove and 0 not upgraded.
Need to get 3,709 kB of archives.
After this operation, 29.7 kB of additional disk space will be used.
Do you want to continue [Y/n]? Y
Get:1 http://us.archive.ubuntu.com/ubuntu/ precise-updates/universe lxc amd64 0.7.5-3ubuntu69 [173 kB]
Get:2 http://get.docker.io/ubuntu/ docker/main lxc-docker amd64 0.6.6 [1,812 B]
Get:3 http://get.docker.io/ubuntu/ docker/main lxc-docker-0.6.6 amd64 0.6.6 [3,299 kB]
Get:4 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main procps amd64 1:3.2.8-11ubuntu6.3 [235 kB]
Fetched 3,709 kB in 2s (1,305 kB/s)
(Reading database ... 164575 files and directories currently installed.)
Preparing to replace lxc 0.7.5-3ubuntu67 (using .../lxc_0.7.5-3ubuntu69_amd64.deb) ...
Unpacking replacement lxc ...
Preparing to replace lxc-docker 0.6.5 (using .../lxc-docker_0.6.6_amd64.deb) ...
Unpacking replacement lxc-docker ...
Processing triggers for man-db ...
Processing triggers for ureadahead ...
(Reading database ... 164576 files and directories currently installed.)
Removing lxc-docker-0.6.5 ...
docker stop/waiting
Processing triggers for ureadahead ...
Selecting previously unselected package lxc-docker-0.6.6.
(Reading database ... 164574 files and directories currently installed.)
Unpacking lxc-docker-0.6.6 (from .../lxc-docker-0.6.6_0.6.6_amd64.deb) ...
Preparing to replace procps 1:3.2.8-11ubuntu6.2 (using .../procps_1%3a3.2.8-11ubuntu6.3_amd64.deb) ...
Unpacking replacement procps ...
Processing triggers for ureadahead ...
Processing triggers for man-db ...
Setting up lxc (0.7.5-3ubuntu69) ...
Setting up lxc dnsmasq configuration.
Setting up lxc-docker-0.6.6 (0.6.6) ...
Installing new version of config file /etc/init.d/docker ...
stop: Unknown instance:
docker start/running, process 15668
Setting up lxc-docker (0.6.6) ...
Setting up procps (1:3.2.8-11ubuntu6.3) ...
procps stop/waiting
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
vagrant@precise64:~$ cat /etc/group | grep docker
docker:x:998: