Undefined method `rescue_responses' for ActionController::Base:Class in Rails Edge

Greetings. I just started a new rails project basing off the edge.1
I prefer to unpack my gems, but when I did so, I received the error
below. Anybody else encounter this and have a suggestion?

$ rake gems:unpack
(in [omitted])
rake aborted!
undefined method `rescue_responses’ for ActionController::Base:Class

(See full trace by running task with --trace)

Thanks,
Ben