safeguard on absolutify rake task

lib/tasks/migrations.rake

@@ -39,6 +39,7 @@ namespace :migrations do
     require File.join(Rails.root,"config/environment")
 
     Photo.all.each do |photo|
+      unless photo.remote_photo_path
         # extract root
         pod_url = photo.person.url
         pod_url.chop! if pod_url[-1,1] == '/'
@@ -58,3 +59,4 @@ namespace :migrations do
       end
     end
   end
+end