current code ignores http header "Accept" if it

has ....,*/* .

It is possible to a device to send
request such that */* appear at the beginning of the
"Accept" header. This patch ensures that "Accept" header
is ignored for such cases too.
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

actionpack/lib/action_dispatch/http/mime_negotiation.rb

@@ -48,7 +48,7 @@ def formats
         @env["action_dispatch.request.formats"] ||=
           if parameters[:format]
             Array(Mime[parameters[:format]])
-          elsif xhr? || (accept && accept !~ /,\s*\*\/\*/)
+          elsif xhr? || (accept && accept !~ /,\s*\*\/\*|\*\/\*,/)
             accepts
           else
             [Mime::HTML]

actionpack/test/controller/mime_responds_test.rb

@@ -216,6 +216,12 @@ def test_js_or_html
     assert_response 406
   end
 
+  def test_json_or_yaml_with_leading_star_star
+    @request.accept = "*/*, application/json"
+    get :json_xml_or_html
+    assert_equal 'HTML', @response.body
+  end
+
   def test_json_or_yaml
     xhr :get, :json_or_yaml
     assert_equal 'JSON', @response.body