Scheint ein PHP Problem zu sein, die Client API kann scheinbar nicht aktualisiert werden. Schade, mit der 4.4.2 gings:
PHP4 comes with an old MySQL client statically linked in. You cannot upgrade it without recompiling PHP from source. This is inconvenient, and if you are using PHP on a hosting provider, you probably don't have privilege to do this.
PHP.net has no plans to release an updated distribution of PHP4 with a newer MySQL client. This issue has been reported several times on bugs.php.net, but they always close the issue with a status of "Bogus", meaning it's not a PHP problem.