Ruby-on-rails – How to universally skip database touches when precompiling assets on Heroku

I'm deploying a Rails 3.1 app to Heroku's Cedar stack. With Heroku Cedar and Rails 3.1, you can compile the assets yourself locally, let Heroku compile them when you push (during "slug compilation"), or have them be compiled just-in-time while the app is running. I want to do the middle option, letting Heroku precompile the assets.

When Heroku runs the assets:precompile task, it errors with "could not connect to server" because the app is trying to connect to the database but no database is available at that stage of slug compilation. The lack of database connection is expected and unavoidable at this point. I'm looking for a way to move past it, because a database connection isn't crucial to asset precompilation.

The part of my app that's trying to connect to the database is Devise. There's a devise_for :users line in routes.rb that wants to look at the User model.

I could just write a rake task that stubs out devise_for and make it a prereq of assets:precompile. I think that would solve my problem, but I'm looking for a more universal solution that I could use on any Rails 3.1 app with this problem on Heroku.

Is there anything out there, or can you conceive of anything that silences database connection errors while still running the app enough to have route and asset path generation?

Obviously if an app needs to read/write data during startup, we can't stub that, but can we fake every ActiveRecord model automatically?