> The package asked me to change root password several times during the
> installation. In all cases, I've just hit 'enter' as an indication that I do
> not want to change it.
And when I re-install (having removed the datadir manually) and do specify the
password when asked, I first get a dialog box saying

---
Unable to set password for the MySQL "root" user
An error occurred while setting the password for the MySQL administrative user. This may have happened because the
account already has a password, or because of a communication problem with the MySQL server.
                                                                                            
You should check the account's password after the package installation.

Please read the /usr/share/doc/mariadb-server-5.1/README.Debian file for more information.
--

and then this output:

Setting up mariadb-server-core-5.1 (5.1.38-ourdelta81) ...
Setting up mariadb-server-5.1 (5.1.38-ourdelta81) ...
 * Stopping MariaDB database server mysqld                                                                          [ OK ] 
091015  2:11:06 [Note] Plugin 'FEDERATED' is disabled.
091015  2:11:06 [ERROR] mysqld: File '/var/lib/mysql/maria_log_control' not found (Errcode: 13)
091015  2:11:06 [ERROR] mysqld: Got error 'Can't open file' when trying to use maria control file '/var/lib/mysql/maria_log_control'
091015  2:11:06 [ERROR] Plugin 'MARIA' init function returned error.
091015  2:11:06 [ERROR] Plugin 'MARIA' registration as a STORAGE ENGINE failed.
091015 02:11:06 [Note] PrimeBase XT (PBXT) Engine 1.0.08d RC loaded...
091015 02:11:06 [Note] Paul McCullagh, PrimeBase Technologies GmbH, http://www.primebase.org
InnoDB: The InnoDB memory heap is disabled
InnoDB: Mutexes and rw_locks use GCC atomic builtins.
091015  2:11:07  InnoDB: highest supported file format is Barracuda.
091015  2:11:07 InnoDB Plugin 1.0.3-6a started; log sequence number 46409
091015  2:11:07 [ERROR] mysqld: Can't find file: './mysql/user.frm' (errno: 13)
ERROR: 1017  Can't find file: './mysql/user.frm' (errno: 13)
091015  2:11:07 [ERROR] Aborting

091015  2:11:07  InnoDB: Starting shutdown...
091015  2:11:08  InnoDB: Shutdown completed; log sequence number 46419
091015 02:11:08 [Note] PrimeBase XT Engine shutdown...
091015  2:11:08 [Note] /usr/sbin/mysqld: Shutdown complete

Replacement succeeded for "/usr/sbin/mysqld".
 * /etc/init.d/mysql: WARNING: /etc/mysql/my.cnf cannot be read. See README.Debian.gz
 * Starting MariaDB database server mysqld                                                                                 
                                                                                                                    [fail]
invoke-rc.d: initscript mysql, action "start" failed.
dpkg: error processing mariadb-server-5.1 (--configure):
 subprocess post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of mariadb-server:
 mariadb-server depends on mariadb-server-5.1; however:
  Package mariadb-server-5.1 is not configured yet.
dpkg: error processing mariadb-server (--configure):
 dependency problems - leaving unconfigured
Processing triggers for libc6 ...
No apport report written because the error message indicates its a followup error from a previous failure.
                                                                                                          ldconfig deferred processing now taking place
Errors were encountered while processing:
 mariadb-server-5.1
 mariadb-server
E: Sub-process /usr/bin/dpkg returned an error code (1)