If partial is rendered in controller, grab format from template

Previously `rendered_format` was set only based on mime types
passed in Accept header, which was wrong if first type from
Accept was different than rendered partial. The fix is to simply
move setting rendered_format to the place where template
is available and grab format from the template. If it fails
we can fallback to formats passed by Accept header.

1 files changed, 8 insertions, 2 deletions

diff --git a/actionpack/lib/action_view/renderer/partial_renderer.rb b/actionpack/lib/action_view/renderer/partial_renderer.rb
index 17aa85555c..25c41f042b 100644
--- a/actionpack/lib/action_view/renderer/partial_renderer.rb
+++ b/actionpack/lib/action_view/renderer/partial_renderer.rb
@@ -221,6 +221,14 @@ module ActionView
       setup(context, options, block)
       identifier = (@template = find_partial) ? @template.identifier : @path
 
+      @lookup_context.rendered_format ||= begin
+        if @template && @template.formats.present?
+          @template.formats.first
+        else
+          formats.first
+        end
+      end
+
       if @collection
         instrument(:collection, :identifier => identifier || "collection", :count => @collection.size) do
           render_collection
@@ -273,8 +281,6 @@ module ActionView
       @block   = block
       @details = extract_details(options)
 
-      @lookup_context.rendered_format ||= formats.first
-
       if String === partial
         @object     = options[:object]
         @path       = partial