Comment 1 for bug 1276229

UPDATE: it appears that removing apparmor allows mysql to start! Apparmor was reinstalled after mysql-server was running correctly and all seems to be working now.

# aptitude purge apparmor
The following packages will be REMOVED:
  apparmor{p}
The following partially installed packages will be configured:
  mysql-server mysql-server-5.5
0 packages upgraded, 0 newly installed, 1 to remove and 4 not upgraded.
Need to get 0 B of archives. After unpacking 1,081 kB will be freed.
The following packages have unmet dependencies:
 apparmor-utils : Depends: apparmor (>= 2.6.1-4ubuntu1) but it is not going to be installed.
The following actions will resolve these dependencies:

     Remove the following packages:
1) apparmor-utils

     Leave the following dependencies unresolved:
2) ubuntu-standard recommends apparmor

Accept this solution? [Y/n/q/?] y
The following packages will be REMOVED:
  apparmor{p} apparmor-utils{a}
The following partially installed packages will be configured:
  mysql-server mysql-server-5.5
0 packages upgraded, 0 newly installed, 2 to remove and 4 not upgraded.
Need to get 0 B of archives. After unpacking 1,609 kB will be freed.
Do you want to continue? [Y/n/?] y
(Reading database ... 122186 files and directories currently installed.)
Removing apparmor-utils ...
Processing triggers for man-db ...
(Reading database ... 122132 files and directories currently installed.)
Removing apparmor ...
 * Clearing AppArmor profiles cache [ OK ]
All profile caches have been cleared, but no profiles have been unloaded.
Unloading profiles will leave already running processes permanently
unconfined, which can lead to unexpected situations.

To set a process to complain mode, use the command line tool
'aa-complain'. To really tear down all profiles, run the init script
with the 'teardown' option."
Purging configuration files for apparmor ...
Processing triggers for man-db ...
Processing triggers for ureadahead ...
Setting up mysql-server-5.5 (5.5.35-0ubuntu0.12.04.2) ...
mysql start/running, process 10541
Setting up mysql-server (5.5.35-0ubuntu0.12.04.2) ...

# ps -ef | grep mysql
mysql 10541 1 0 09:55 ? 00:00:00 /usr/sbin/mysqld
root 10717 4147 0 09:56 pts/2 00:00:00 grep mysql

# aptitude install apparmor
The following NEW packages will be installed:
  apparmor
0 packages upgraded, 1 newly installed, 0 to remove and 4 not upgraded.
Need to get 0 B/357 kB of archives. After unpacking 1,081 kB will be used.
Preconfiguring packages ...
Selecting previously unselected package apparmor.
(Reading database ... 122030 files and directories currently installed.)
Unpacking apparmor (from .../apparmor_2.7.102-0ubuntu3.9_amd64.deb) ...
Processing triggers for ureadahead ...
Processing triggers for man-db ...
Setting up apparmor (2.7.102-0ubuntu3.9) ...
 * Starting AppArmor profiles [ OK ]
 * Reloading AppArmor profiles

# start mysql
mysql start/running, process 18023