Fix commit 7bbb4ff84f so it's backwards-compatible

lib/liquid/file_system.rb

@@ -14,7 +14,7 @@ module Liquid
   # This will parse the template with a LocalFileSystem implementation rooted at 'template_path'.
   class BlankFileSystem
     # Called by Liquid to retrieve a template file
-    def read_template_file(context, template_name)
+    def read_template_file(template_path, context)
       raise FileSystemError, "This liquid context does not allow includes."
     end
   end
@@ -38,8 +38,7 @@ module Liquid
       @root = root
     end
     
-    def read_template_file(context, template_name)
-      template_path = context[template_name]
+    def read_template_file(template_path, context)
       full_path = full_path(template_path)
       raise FileSystemError, "No such template '#{template_path}'" unless File.exists?(full_path)
       

lib/liquid/tags/include.rb

@@ -22,12 +22,10 @@ module Liquid
   
     def parse(tokens)      
     end
-  
+    
     def render(context)      
-      file_system = context.registers[:file_system] || Liquid::Template.file_system
-      source  = file_system.read_template_file(context, @template_name)
+      source = _read_template_from_file_system(context)
       partial = Liquid::Template.parse(source)      
-      
       variable = context[@variable_name || @template_name[1..-2]]
       
       context.stack do
@@ -50,6 +48,21 @@ module Liquid
         end
       end
     end
+   
+    private
+      def _read_template_from_file_system(context)
+        file_system = context.registers[:file_system] || Liquid::Template.file_system
+      
+        # make read_template_file call backwards-compatible.
+        case file_system.method(:read_template_file).arity
+        when 1
+          file_system.read_template_file(context[@template_name])
+        when 2
+          file_system.read_template_file(context[@template_name], context)
+        else
+          raise ArgumentError, "file_system.read_template_file expects two parameters: (template_name, context)"
+        end
+      end
   end
 
   Template.register_tag('include', Include)