Comment 3 for bug 82760

Well, you have to follow the instructions in /usr/share/doc/mediawiki1.7/README.Debian.gz

Here are the steps:

Upgrading from 1.5 to 1.7 package:
        The upgrade path is really easy compared to 1.4 -> 1.5 upgrade.
        .
        A rapid sketch of what you need to do is as follow:
        1) Dump your database to a text file.
                mysqldump --add-drop-table -u <user> -p <my-database> > /path/to/file.sql
        2) Copy the configuration files from /etc/mediawiki1.5 to /var/lib/mediawiki1.7 and make the
m writable for
             your webserver user -- usualy www-data.
                cp /etc/mediawiki/LocalSettings.php /var/lib/mediawiki1.7
                cp /etc/mediawiki/AdminSettings.php /var/lib/mediawiki1.7 (if exists)
        3) change your working path to /var/lib/mediawiki1.5:
                cd /var/lib/mediawiki1.7
        4) Execute the update script:
                php maintenance/update.php
           This shall need a proper php5 binary, as provided in php5-cli
        5) Execute the rebuildall script:
                php maintenance/rebuildall.php
        6) Copy the old upload directory:
                cp -rf /var/lib/mediawiki1.5/upload/* /var/lib/mediawiki1.7/upload/
        You are done !
        See configuration section of /etc/mediawiki1.7.confile-location for details about
        the place where configuration files may be placed.