[debian-mysql] Bug#845648: Bug#845648: mention how to deal with Pre-4.1 password hash found. It is deprecated and will be removed in a future release. Please upgrade it to a new format warning

[積丹尼 Dan Jacobson]

# systemctl enable mysql
Synchronizing state of mysql.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable mysql
insserv: warning: current start runlevel(s) (empty) of script `mysql' overrides LSB defaults (2 3 4 5).
insserv: warning: current stop runlevel(s) (0 1 2 3 4 5 6) of script `mysql' overrides LSB defaults (0 1 6).
# aptitude install
The following partially installed packages will be configured:
  mysql-server  mysql-server-5.7
No packages will be installed, upgraded, or removed.
0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B of archives. After unpacking 0 B will be used.
Do you want to continue? [Y/n/?]
Setting up mysql-server-5.7 (5.7.16-1) ...
Renaming removed key_buffer and myisam-recover options (if present)
Checking if update is needed.
Checking server version.
Running queries to upgrade MySQL server.
mysql_upgrade: (non fatal) [WARNING] 1642: Pre-4.1 password hash found. It is deprecated and will be removed in a future release. Please upgrade it to a new format.
Checking system database.
mysql.columns_priv                                 OK
mysql.db                                           OK
mysql.engine_cost                                  OK...

I think some --skip-secure-* argument like mentioned in
http://mysqlblog.fivefarmers.com/2012/05/30/why-your-pre-4-1-client-wont-like-mysql-5-6/
was finally removed or something, so now I am getting the warnings.