Drops textgroup support.
Update assumes i18n migrated this data before the update happened. Core never used textgroups for anything, so it is not our job to find a place for the data elsewhere.
function locale_update_8000() {
$subquery = db_select('locales_source', 'ls')
->fields('ls', array(
'lid',
))
->condition('ls.textgroup', 'default', '<>');
db_delete('locales_target')
->condition('lid', $subquery, 'IN')
->execute();
db_delete('locales_source')
->condition('textgroup', 'default', '<>')
->execute();
db_drop_field('locales_source', 'textgroup');
}