Use relative path for `path` Liquid variable in Documents

lib/jekyll/document.rb

@@ -232,8 +232,7 @@ module Jekyll
         Utils.deep_merge_hashes data, {
           "output"        => output,
           "content"       => content,
-          "path"          => path,
-          "relative_path" => relative_path,
+          "path"          => relative_path,
           "url"           => url,
           "collection"    => collection.label
         }

test/test_document.rb

@@ -44,6 +44,10 @@ class TestDocument < Test::Unit::TestCase
       assert_equal @document.to_liquid['collection'], "methods"
     end
 
+    should "output its relative path as path in Liquid" do
+      assert_equal @document.to_liquid['path'], "_methods/configuration.md"
+    end
+
   end
 
   context "a document as part of a collection with frontmatter defaults" do