Bring back rendering templates that start with / in nested structures

actionpack/lib/action_view/lookup_context.rb

@@ -152,6 +152,7 @@ module ActionView
       def normalize_name(name, prefixes) #:nodoc:
         prefixes = nil if prefixes.blank?
         parts    = name.to_s.split('/')
+        parts.shift if parts.first.empty?
         name     = parts.pop
 
         return name, prefixes || [""] if parts.empty?

actionpack/test/controller/new_base/render_template_test.rb

@@ -201,4 +201,26 @@ module RenderTemplate
       assert_status 200
     end
   end
+
+  module Compatibility
+    class WithoutLayoutController < ActionController::Base
+      self.view_paths = [ActionView::FixtureResolver.new(
+        "test/basic.html.erb" => "Hello from basic.html.erb",
+        "shared.html.erb"     => "Elastica"
+      )]
+
+      def with_forward_slash
+        render :template => "/test/basic"
+      end
+    end
+
+    class TestTemplateRenderWithForwardSlash < Rack::TestCase
+      test "rendering a normal template with full path starting with a leading slash" do
+        get "/render_template/compatibility/without_layout/with_forward_slash"
+
+        assert_body "Hello from basic.html.erb"
+        assert_status 200
+      end
+    end
+  end
 end