MySQL Server automatic update followed by restart: ERROR: 1064 You have an error in your SQL syntax; mysql.user add column

At first time in the morning I was looking to "show engine innodb status" and noticed low values in SEMAPHORES, which leads to the conclusion of an unauthorized restart.
After research I've found that Ubuntu Server made an update to MySQL Server 5.5 package and initiated a restart of the MySQL service.
Some errors was issued after update:

ERROR: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1
150422 6:30:27 [ERROR] Aborting

Searching the web I've found that the same error appears to others and came from:
mysql-server-5.5.postinst
even in year 2012, 2013, 2014.
Besides that, another errors came after the restart issued after the above error:
ERROR: 1364 Field 'ssl_cipher' doesn't have a default value
ERROR: 1050 Table 'plugin' already exists

so... HEY, what's going on?? Why are you messing things up with old UNVERIFIED update scripts??? And why are you doing restarts without admin's consent?
At least, put a question before the update:
"An update is pending for MySQL Server 5.5. DO YOU FEEL LUCKY, PUNK? [yN]"

Best regards!
Tinel Barb

PS1: the columns the script tried to add were already implemented since installation.
PS2: as a test, I'm curious what you'll find important for a reply ;)

PS3: Bob Proulx <bob[antiposix[proulx.com> suggested at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=708176 the folowing code in order to catch exceptions while updating the structure on mysql.user. I think that is a very good code to avoid braking updates.

***CODE***
    new_mysql_columns="
        Create_view_priv
        Show_view_priv
        Create_routine_priv
        Alter_routine_priv
        Create_user_priv
        Event_priv
        Trigger_priv
        Create_tablespace_priv
        "
    for col in $new_mysql_columns; do
      printf "USE mysql;\n ALTER TABLE user ADD column $col enum('N','Y') CHARACTER SET utf8 NOT NULL DEFAULT 'N';\n" | $MYSQL_BOOTSTRAP 2>&1 | sed "/^ERROR:.*Duplicate column name '$col'/d;/Aborting/d" | $ERR_LOGGER
    done
***END-CODE***