diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index 8ed01f39e99d06f00719bddf975ebc857ee30013..04bfdd4c7971f7e6b2e7fca5e916afd369495d7f 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Fixed that setting RAILS_ASSET_ID to "" should not add a trailing slash after assets #6454 [BobSilva/chrismear]
+
 * Force *_url named routes to show the host in ActionView [Rick]
 
   <%= url_for ... %> # no host
diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index 93f04968f99dacd86b5e6dec2144305aa1e1a224..086880b06d174d3b9e35baa7b8bf586aa4e662c1 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -159,11 +159,13 @@ def image_tag(source, options = {})
       private
         def compute_public_path(source, dir, ext)
           source = source.dup
-          source  = "/#{dir}/#{source}" unless source.first == "/" || source.include?(":")
-          source << ".#{ext}" unless source.split("/").last.include?(".")
-          source << '?' + rails_asset_id(source) if defined?(RAILS_ROOT) && %r{^[-a-z]+://} !~ source
-          source  = "#{@controller.request.relative_url_root}#{source}" unless %r{^[-a-z]+://} =~ source
-          source = ActionController::Base.asset_host + source unless source.include?(":")
+          source << ".#{ext}" if File.extname(source).blank?
+          unless source =~ %r{^[-a-z]+://}
+            source = "/#{dir}/#{source}" unless source[0] == ?/
+            asset_id = rails_asset_id(source)
+            source << '?' + asset_id if defined?(RAILS_ROOT) and not asset_id.blank?
+            source = "#{ActionController::Base.asset_host}#{@controller.request.relative_url_root}#{source}"
+          end
           source
         end
         
diff --git a/actionpack/lib/action_view/helpers/capture_helper.rb b/actionpack/lib/action_view/helpers/capture_helper.rb
index 28b3e29967a4f2fdfc63707aac60cf2bd70dcfd1..497ce093ebda2e09950b6aabd3363d14d6a9ebb0 100644
--- a/actionpack/lib/action_view/helpers/capture_helper.rb
+++ b/actionpack/lib/action_view/helpers/capture_helper.rb
@@ -89,7 +89,7 @@ def capture(*args, &block)
       # named @@content_for_#{name_of_the_content_block}@. So <tt><%= content_for('footer') %></tt>
       # would be avaiable as <tt><%= @content_for_footer %></tt>. The preferred notation now is
       # <tt><%= yield :footer %></tt>.
-      def content_for(name, &block)
+      def content_for(name, content = nil, &block)
         eval "@content_for_#{name} = (@content_for_#{name} || '') + capture(&block)"
       end
 
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index e8320291fe1c6173af549178a0883ca8ef1bf064..4b941921cf9c51713a2592dce53964c8cbce3170 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -70,7 +70,8 @@ def teardown
     %(stylesheet_link_tag("/dir/file")) => %(<link href="/dir/file.css" media="screen" rel="Stylesheet" type="text/css" />),
     %(stylesheet_link_tag("dir/file")) => %(<link href="/stylesheets/dir/file.css" media="screen" rel="Stylesheet" type="text/css" />),
     %(stylesheet_link_tag("style", :media => "all")) => %(<link href="/stylesheets/style.css" media="all" rel="Stylesheet" type="text/css" />),
-    %(stylesheet_link_tag("random.styles", "/css/stylish")) => %(<link href="/stylesheets/random.styles" media="screen" rel="Stylesheet" type="text/css" />\n<link href="/css/stylish.css" media="screen" rel="Stylesheet" type="text/css" />)
+    %(stylesheet_link_tag("random.styles", "/css/stylish")) => %(<link href="/stylesheets/random.styles" media="screen" rel="Stylesheet" type="text/css" />\n<link href="/css/stylish.css" media="screen" rel="Stylesheet" type="text/css" />),
+    %(stylesheet_link_tag("http://www.example.com/styles/style")) => %(<link href="http://www.example.com/styles/style.css" media="screen" rel="Stylesheet" type="text/css" />)
   }
 
   ImagePathToTag = {
@@ -141,6 +142,12 @@ def test_preset_asset_id
     assert_equal %(<img alt="Rails" src="/images/rails.png?4500" />), image_tag("rails.png")
   end
 
+  def test_preset_empty_asset_id
+    Object.send(:const_set, :RAILS_ROOT, File.dirname(__FILE__) + "/../fixtures/")
+    ENV["RAILS_ASSET_ID"] = ""
+    assert_equal %(<img alt="Rails" src="/images/rails.png" />), image_tag("rails.png")
+  end
+
   def test_url_dup_image_tag
     Object.send(:const_set, :RAILS_ROOT, File.dirname(__FILE__) + "/../fixtures/")
     img_url = '/images/rails.png'