Rack Middleware breaks RSpec integration tests

lib/versionist/middleware.rb

@@ -19,7 +19,7 @@ def call(env)
 
     def _call(env)
       request = ::Rack::Request.new(env)
-      strategy = Versionist.configuration.versioning_strategies.detect {|vs| vs.is_a?(Versionist::VersioningStrategy::Header) && vs.config[:header] == ACCEPT && env[HTTP_ACCEPT].include?(vs.config[:value])}
+      strategy = Versionist.configuration.versioning_strategies.detect {|vs| vs.is_a?(Versionist::VersioningStrategy::Header) && vs.config[:header] == ACCEPT && env[HTTP_ACCEPT].try(:include?, vs.config[:value])}
       if !strategy.nil?
         entries = env[HTTP_ACCEPT].split(',')
         index = -1

spec/middleware_spec.rb

@@ -35,5 +35,11 @@
       status, headers, response = described_class.new(@app).call(request)
       response[0].should == "audio/*; q=0.2, audio/basic, application/json, application/vnd.mycompany.com-v2.3.0"
     end
+
+    it "should not alter the header if the accept header is not present" do
+      request = Rack::MockRequest.env_for("/foos", :lint => true, :fatal => true)
+      status, headers, response = described_class.new(@app).call(request)
+      response[0].should be_nil
+    end
   end
 end