Factor out a `read_data_file` call to keep things clean

lib/jekyll/site.rb

@@ -258,13 +258,20 @@ module Jekyll
         if File.directory?(path)
           read_data_to(path, data[key] = {})
         else
+          data[key] = read_data_file(path)
+        end
+      end
+    end
+    
+    # Determines how to read a data file.
+    #
+    # Returns the contents of the data file.
+    def read_data_file(path)
       case File.extname(path).downcase
       when '.csv'
-            data[key] = CSV.read(path, :headers => true).map(&:to_hash)
+        CSV.read(path, :headers => true).map(&:to_hash)
       else
-            data[key] = SafeYAML.load_file(path)
-          end
-        end
+        SafeYAML.load_file(path)
       end
     end