norman/friendly_id — comment on commit ac7c88580513eac45c857cf80df1dd46c58c3421
File:  line 0
By norman:

For 3.x, it was released a long time ago, but it's since been removed in 4.0.

This is because 4.0 generates the slug with a before_validation callback, and keeps the slug in the same table as the model, meaning you can now just use regular Active Record validations for this.

4.0 still includes a basic reserved words functionality by default, but only to avoid letting people use slugs like "new" that could mess up an application's routes.