It would've saved me a lot of time if I'd realised sooner that, as far as I can tell, you can't use Bundler with the Rails 2.x gems if you need a Git repository

It would've saved me a lot of time if I'd realised sooner that, as far as I can tell, you can't use Bundler with the Rails 2.x gems if you need a Git repository as the gem source (e.g. because you've forked them) because the Rails 2.x repo contains multiple gems but has no gemspec explaining that. [Although maybe adding a backported gemspec to the fork would work?] Once I finally gave up trying to use Bundler to manage my forked Rails 2.x and just left vendor/rails as a submodule, all the rest of the bundled gems worked beautifully.