only halt execution in last_modified if status is currently 200 (to confrom with RFC 2616)

CHANGES

@@ -82,6 +82,9 @@
  * Conditional requests on `etag` helper now work properly for unsafe HTTP
    methods. (Matthew Schinckel, Konstantin Haase)
 
+ * The `last_modified` helper does not stop execution and change the status code
+   if the status code is something different than 200. (Konstantin Haase)
+
  * `Sinatra::Base.run!` now prints to stderr rather than stdout. (Andrew
    Armenia)
 

lib/sinatra/base.rb

@@ -356,7 +356,7 @@ module Sinatra
       time = time_for time
       response['Last-Modified'] = time.httpdate
 
-      unless env['HTTP_IF_NONE_MATCH']
+      if status == 200 and not env['HTTP_IF_NONE_MATCH']
         # compare based on seconds since epoch
         since = Time.httpdate(env['HTTP_IF_MODIFIED_SINCE']).to_i
         halt 304 if since >= time.to_i

test/helpers_test.rb

@@ -858,6 +858,20 @@ class HelpersTest < Test::Unit::TestCase
       assert ! response['Last-Modified']
     end
 
+    it 'does not change a status other than 200' do
+      mock_app do
+        get '/' do
+          status 299
+          last_modified Time.at(0)
+          'ok'
+        end
+      end
+
+      get('/', {}, 'HTTP_IF_MODIFIED_SINCE' => 'Sun, 26 Sep 2030 23:43:52 GMT')
+      assert_status 299
+      assert_body 'ok'
+    end
+
     [Time.now, DateTime.now, Date.today, Time.now.to_i,
       Struct.new(:to_time).new(Time.now) ].each do |last_modified_time|
       describe "with #{last_modified_time.class.name}" do