Use PDO in provision's db_server instead of "old school" mysql (that may be a failure if only mysqli if available)

As requested by anarcat I open this issue separately from the discussion here http://drupal.org/node/553348

Nearly Verbatim text, sorry for the late laziness

"Got it :)"

Call me stubborn but I wanted to find the bottom of it and for once stubbornness paid of because I would have had the same problem with RC4.

I managed to install remote Eclipse-PDT - CLI debugging through my NAT-ed home computer to my main coloc server, something that could prove useful (for me at least) in the future (if it is such a common skill forget I ever wrote this sentence but if some people are interested I could write a short doc)
This lead to the line

$connection = @mysql_connect(drush_get_option('master_db_host'), drush_get_option('master_db_user'), drush_get_option('master_db_passwd'));

as the one that provoked a run-time failure and thus the command failure.

Now guess what ?

On my FreeBSD box I installed the PhP extensions with mysqli because it is the recommended "modern" PhP interface for Mysql, but not the "Mysql" extensions proper.

It is mandatory to have the "old school mysql" extensions support and not only the "mysqli extensions" to use Drush / AEgir.
PHP Mysql supports must be understood in the literal sense for now. :)

That information is somewhat hidden in the apt-get install php5 php5-cli php5-mysql line in INSTALL.TXT under a debian-ism :)

Since Drupal supports either Mysql extensions or MysqlI extensions, I was none the wiser on the Drupal front but obviously the AEgir modules do not .... hence the problem.

I will now wipe out the full install and redo it following step by step the new RC4 instruction and report anything unclear, odd or non obvious.

I'll have questions on the recommended file structure and upgrade policy (I have bad gut feelings about it) but I will first follow the instruction to the letter and ask about it after that.

Thanks a lot to the AEgir team.