Revert 299f088..e0befca

This rolls back to commit 299f08877fbc82d9ab4e1307c6cddac9f2ff0e38.
Revert e0befca..29f5807

This rolls back to commit e0befca9a6887703aa2e6b5494624a7fa877d761.
Revert 720b740..f465980

This rolls back to commit 720b7408f1ab29709b699426c97e74b6cfe41858.
DbManager::checkUserExists($user)