api06: Fix diff uploading (still doesn't give a useful response):

Modification and deletion works fine now.  Rollback also works apparently.
Just auto increment doesn't get reset.

app/controllers/way_controller.rb

@@ -51,35 +51,18 @@ class WayController < ApplicationController
       new_way = Way.from_xml(request.raw_post)
 
       if new_way and new_way.id == way.id
-        unless update_internal(way, new_way)
-          render :text => "", :status => :precondition_failed
-        else
-          render :nothing => true
-        end
+	way.update_from(new_way, @user)
+	render :nothing => true
       else
         render :nothing => true, :status => :bad_request
       end
+    rescue OSM::APIPreconditionFailedError
+      render :text => "", :status => :precondition_failed
     rescue ActiveRecord::RecordNotFound
       render :nothing => true, :status => :not_found
     end
   end
 
-  def update_internal way, new_way
-    way = Way.find(new_way.id) if way.nil?
-
-    if !new_way.preconditions_ok?
-      return false
-    else
-      way.user_id = @user.id
-      way.tags = new_way.tags
-      way.nds = new_way.nds
-      way.visible = true
-      way.save_with_history!
-
-      return true
-    end
-  end
-
   # This is the API call to delete a way
   def delete
     begin