Permission leak when deleting group

Create a Project group.
Add projects to it.
Delete the group.

All the roles and permissions created for the projects and groups remain in the Database and interface, with no way to delete them.
Over time, when many groups are created and deleted for versioning, this create a lot of orphans permissions and roles that slows down access.

The only way to purge those orphan roles are to delete them directly in the database, a task that is complicated by the various table relations.

When deleting a group, the associated permissions and role should be automatically deleted or at the very least, prompted for deletion.