'redmine' 'redmine-mysql' fail to install with 'ruby' (1.9.3)

Hello,

To sum things up, I think the 'redmine' 2.3.1-1 package is not compatible with 'ruby' (indirectly the latest 'ruby1.9.1' 1.9.3.194-8.1ubuntu2), but only with the older 'ruby1.8' (1.8.7.358-7ubuntu2) , which doesn't match with the 'redmine' package dependencies at the moment.

System:
---
$ lsb_release -rd
Description: Ubuntu 13.10
Release: 13.10
$ sudo apt-cache policy redmine
redmine:
  Installed: 2.3.1-1
  Candidate: 2.3.1-1
  Version table:
 *** 2.3.1-1 0
        500 http://fr.archive.ubuntu.com/ubuntu/ saucy/universe amd64 Packages
        100 /var/lib/dpkg/status
---

Supposed-expected and actual:
---
Expected: install succeeds and '/etc/redmine/default/database.yml' contains 'adapter: mysql2'
Actual: install fails (E: Sub-process /usr/bin/dpkg returned an error code (1)), and '/etc/redmine/default/database.yml' contains 'adapter: mysql'
---

Going into details, I meet this error when 'sudo aptitude install redmine redmine-mysql' on Saucy 13.10:
---
Creating config file /etc/redmine/default/session.yml with new version
A new secret session key has been generated in /etc/redmine/default/session.yml
Populating database for redmine instance "default".
This may take a while.
rake aborted!
Please install the mysql adapter: `gem install activerecord-mysql-adapter` (cannot load such file -- mysql)

Tasks: TOP => db:migrate => environment
(See full trace by running task with --trace)
Error when running rake db:migrate, check database configuration.
dpkg: error processing redmine (--configure):
 subprocess installed post-installation script returned error exit status 1
Processing triggers for libc-bin ...
Errors were encountered while processing:
 redmine
E: Sub-process /usr/bin/dpkg returned an error code (1)
---

Looking for the 'redmine' and 'activerecord-mysql-adapter' keywords on the web sent me there:
---
http://stackoverflow.com/questions/9609985/please-install-mysql-adapter-gem-install-activerecord-mysql-adapter
http://www.redmine.org/projects/redmine/wiki/RedmineInstall (look for the "Example for a MySQL database using ruby 1.9 (adapter must be set to mysql2)" pattern in this one)
---

And indeed, before purging the failed install, here is the '/etc/redmine/default/database.yml' content:
---
$ sudo cat /etc/redmine/default/database.yml
production:
  adapter: mysql
  database: redmine_default
  host: localhost
  port:
  username: redmine
  password:
  encoding: utf8
---

By the way, I'm still a linux rookie, and an erroneous packages management on my side could be the cause.

Here is my install context:
---
1/ initial install: Raring 13.04, in a virtualbox guest with snapshots taken after each successfull configuration or before each unmastered one
2/ 'redmine' install through repositories
3/ flawless (it seems) upgrade to Saucy 13.10, including the 'redmine' upgrade, in order to have more ruby1.9.3-related dependencies
4/ purge of 'redmine', in order to purge 'ruby' 1.8 and upgrade it to 1.9.1 (1.9.3.194-8.1ubuntu2), for a manual gitlab install without having to 'gem install' but installing 'ruby-charlock-holmes' from repositories
5/ flawless manual install of gitlab, relying on the repositories ruby 1.9.1 (1.9.3.194-8.1ubuntu2)
6/ failed new install of redmine
---

So I try to only install ruby1.9.1-related packages only, not to mess up with its 1.8 version, but it doesn't seem to be possible, since the 'redmine' package, and the 'libapache2-mod-passenger' also, both have some ruby1.8 dependencies.

Feel free to ask me more useful info if needed: I stay tuned :) Thanks for free software