Remove Status key from response_headers as per the Rack protocol

see Rack::Lint, https://github.com/rack/rack/blob/master/lib/rack/lint.rb

Author: janraasch

lib/rack/reverse_proxy.rb

@@ -84,6 +84,7 @@ def proxy(env, source_request, matcher)
       # Let rack set the transfer-encoding header
       response_headers = Rack::Utils::HeaderHash.new Proxy.normalize_headers(format_headers(target_response.headers))
       response_headers.delete('Transfer-Encoding')
+      response_headers.delete('Status')
 
       # Replace the location header with the proxy domain
       if response_headers['Location'] && options[:replace_response_host]

spec/rack/reverse_proxy_spec.rb

@@ -62,14 +62,23 @@ def app
       a_request(:get, 'http://example.com/test/stuff').with(:headers => {'X-Forwarded-Host' => 'example.org'}).should have_been_made
     end
 
-    it 'should format the headers correctly to avoid duplicates' do
+    it 'should should not produce headers with a Status key' do
       stub_request(:get, 'http://example.com/2test').to_return({:status => 301, :headers => {:status => '301 Moved Permanently'}})
 
       get '/2test'
 
       headers = last_response.headers.to_hash
-      headers['Status'].should == "301 Moved Permanently"
-      headers['status'].should be_nil
+      headers['Status'].should be_nil
+    end
+
+    it 'should format the headers correctly to avoid duplicates' do
+      stub_request(:get, 'http://example.com/2test').to_return(:headers => {:date => 'Wed, 22 Jul 2015 11:27:21 GMT'})
+
+      get '/2test'
+
+      headers = last_response.headers.to_hash
+      headers['Date'].should == 'Wed, 22 Jul 2015 11:27:21 GMT'
+      headers['date'].should be_nil
     end
 
     it 'should format the headers with dashes correctly' do