FIX: do not allow tag with name 'none' (PR #9867)


We should be using sql here instead of using the AR models. It’s annoying because there are so many associations to delete… This case is so simple it might be ok.

I think it’s better if we iterate over the associations [:tag_users, :topic_tags, ... ] and delete the rows with sql. delete from #{table_name} where tag_id = :none_tag_id

Use sql in the migration instead of tag.destroy.

Update the migration to use SQL.