Just pulled the latest master of MediaWiki core on a fresh Ubuntu install and tried to configure the wiki. As soon as I finished the page where I name the wiki, I got an internal error and had to abort the process:

[92a4e9f4] /mw-config/index.php?page=Name DBAccessError from line 364 of /var/www/html/includes/db/LBFactory.php: Mediawiki tried to access the database via wfGetDB(). This is not allowed.

Backtrace:

#0 /var/www/html/includes/GlobalFunctions.php(3619): LBFactoryFake->getMainLB(boolean)
#1 /var/www/html/includes/User.php(348): wfGetLB()
#2 /var/www/html/includes/User.php(2992): User->load()
#3 /var/www/html/includes/User.php(3007): User->getGroups()
#4 /var/www/html/includes/password/UserPasswordPolicy.php(103): User->getEffectiveGroups()
#5 /var/www/html/includes/password/UserPasswordPolicy.php(74): UserPasswordPolicy->getPoliciesForUser(User)
#6 /var/www/html/includes/User.php(860): UserPasswordPolicy->checkUserPassword(User, string)
#7 /var/www/html/includes/User.php(808): User->checkPasswordValidity(string)
#8 /var/www/html/includes/installer/WebInstallerPage.php(912): User->getPasswordValidity(string)
#9 /var/www/html/includes/installer/WebInstallerPage.php(739): WebInstallerName->submit()
#10 /var/www/html/includes/installer/WebInstaller.php(280): WebInstallerName->execute()
#11 /var/www/html/mw-config/index.php(77): WebInstaller->execute(array)
#12 /var/www/html/mw-config/index.php(36): wfInstallerMain()
#13 {main}