Just installed the newest version of amazon-ecs (0.5.6), and received this in my Rails application (using ruby-hmac version 0.3.2):
You have a nil object when you didn't expect it! The error occurred while evaluating nil.reset_key

Backtrace:

/Library/Ruby/Gems/1.8/gems/ruby-hmac-0.3.2/lib/hmac.rb:101:in `digest'

/Users/stderr/Projects/blah/vendor/gems/amazon-ecs-0.5.6/lib/amazon/ecs.rb:250:in `sign_request'

/Users/stderr/Projects/blah/vendor/gems/amazon-ecs-    0.5.6/lib/amazon/ecs.rb:232:in `prepare_url'

/Users/stderr/Projects/blah/vendor/gems/amazon-ecs- 0.5.6/lib/amazon/ecs.rb:107:in `send_request'

/Users/stderr/Projects/blah/vendor/gems/amazon-ecs-0.5.6/lib/amazon/ecs.rb:97:in `item_lookup'

Any ideas why this is happening? I can use HMAC::SHA256.digest with the same key fine from irb.