function configure_ml2_extension_drivers {
    if is_neutron_legacy_enabled; then
        # NOTE(yamamoto): This overwrites what Devstack's neutron module set,
        # with the latest set of drivers.
        # While we modifies Q_ML2_PLUGIN_EXT_DRIVERS (via
        # neutron_ml2_extension_driver_add calls) in the post-config phase,
        # lib/neutron-legcay populates this in "configure_neutron", which is
        # before post-config.
        # REVISIT(yamamoto): Probably this ought to be in lib/neutron-legcay
        iniset /$NEUTRON_CORE_PLUGIN_CONF ml2 extension_drivers ${Q_ML2_PLUGIN_EXT_DRIVERS}
    fi
}