Remove deprecated logic to render templates starting with /

  render :template => "/foo/bar"

actionpack/lib/action_controller/metal/compatibility.rb

@@ -21,7 +21,6 @@ def _normalize_options(options)
     end
 
     def render_to_body(options)
-      options[:template].sub!(/^\//, '') if options.key?(:template)
       super || " "
     end
 

actionpack/test/controller/new_base/render_template_test.rb

@@ -201,26 +201,4 @@ class TestWithLayout < Rack::TestCase
       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