Case: When base_phone is installed --before-- account, account module installs l10n_fr (generate fiscal year and periods (see https://github.com/odoo/odoo/blob/8.0/addons/account/account_pre_install.yml and https://github.com/odoo/odoo/blob/8.0/addons/account/installer.py#L163)) and then account_demo.xml fails because fiscalyear and periods already exists.