Duplicate the middleware settings before manipulating them on endpoint compilation.

Author: Michael Bleigh

lib/grape/endpoint.rb

@@ -226,6 +226,7 @@ def build_middleware
       b.use Grape::Middleware::Formatter, :default_format => settings[:default_format] || :json
 
       aggregate_setting(:middleware).each do |m|
+        m = m.dup
         block = m.pop if m.last.is_a?(Proc)
         if block
           b.use *m, &block

spec/grape/api_spec.rb

@@ -414,6 +414,19 @@ def call(env)
         get '/'
         last_response.body.should == 'true'
       end
+
+      it 'should not destroy the middleware settings on multiple runs' do
+        block = lambda{ }
+        subject.use PhonyMiddleware, &block
+        subject.get '/' do
+          env['phony.block'].inspect
+        end
+
+        2.times do 
+          get '/'
+          last_response.body.should == 'true'
+        end
+      end
     end
   end
   describe '.basic' do