fix pattern

_config.yml

@@ -33,7 +33,7 @@ collections:
     permalink: "/:title"
   repo:
     output: true
-    permalink: ":author/:title"
+    permalink: ":doc_author/:title"
   news:
     output: true
     permalink: /news/:year/:month/:day/:title

_plugins/author_permalink.rb

@@ -1,8 +1,8 @@
 module Jekyll
     module Drops
       class UrlDrop < Drop
-        def author
-          @obj.author
+        def doc_author
+          @obj.data['author']
         end
       end
     end