Scenario:
- The user is upgrading their MW install and, ignorantly, erases their LS.php
- The database, where all the "important" stuff is found, is left untouched.
New Installer will see the DB and upgrade it. However, $wgUpgradeKey and $wgSecretKey will both be set to empty values (i.e. "") in the LS.php which is made available for downloading.
Version: 1.17.x
Severity: major