Don't set Content-Length on 304 responses

Commit 8aad8c claimed to do this, but it checks for the 304 status too early, before handle_conditional_get! has overridden it.

[#958 state:resolved]
Signed-off-by: NJonathan del Strother <jon.delStrother@bestbefore.tv>
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

actionpack/lib/action_controller/response.rb

@@ -129,8 +129,8 @@ def assign_default_content_type_and_charset!
 
     def prepare!
       assign_default_content_type_and_charset!
-      set_content_length!
       handle_conditional_get!
+      set_content_length!
       convert_content_type!
     end
 

actionpack/test/controller/render_test.rb

@@ -1321,6 +1321,12 @@ def test_render_against_etag_request_should_304_when_match
     assert @response.body.empty?
   end
 
+  def test_render_against_etag_request_should_have_no_content_length_when_match
+    @request.if_none_match = etag_for("hello david")
+    get :render_hello_world_from_variable
+    assert !@response.headers.has_key?("Content-Length")
+  end
+
   def test_render_against_etag_request_should_200_when_no_match
     @request.if_none_match = etag_for("hello somewhere else")
     get :render_hello_world_from_variable