AsyncRack does nasty things with Rack namespace

[jonasschneider]

[1] pry(main)> require 'async-rack'
=> true
[2] pry(main)> require 'rack/head'
NameError: uninitialized constant Rack::Head
from /Users/jonas/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/async-rack-0.5.1/lib/async_rack/async_callback.rb:7:in `const_get'
[3] pry(main)> Rack::Head
=> AsyncRack::Head

What am I doing wrong?
Bonus:

# inserted by me before line 7 of async-rack-0.5.1/lib/async_rack/async_callback.rb
puts [namespace.constants.include?(name), namespace.const_defined?(name)]
# => [true, false]

[rkh]

Oh, yeah, I think you don't wanna use AsyncRack, instead you wanna use Sinatra's stream helper, throw :async directly or the new hijacking API.