Edge rails, single table inheritance and keeping multiple classes in a single file

So is the official stance as per edge rails that multiple class
definitions must go into separate files? I was trying to use STI with
acts_as_attachment, to have all my attachment classes go into a single
file, for example:


class Attachment < ActiveRecord::Base

class UserPicture < Attachment
belongs_to :user, :foreign_key => 'owner_id'
acts_as_attachment ...

but I get the error: superclass mismatch for class UserPicture

when using "model :attachment" in my controller.. This used to work
under rails 1.1.6. I found the following bug report regarding this


Just wondering if this is something that's going to eventually be
fixed, or if from now on, we should start putting all separate classes
into individual files? Thanks,