Don't raise error if a record already exists.

Don’t raise error if a record already exists.

diff --git a/lib/tasks/posts.rake b/lib/tasks/posts.rake
index 0395c75..fe24d90 100644
--- a/lib/tasks/posts.rake
+++ b/lib/tasks/posts.rake
@@ -472,7 +472,8 @@ task 'posts:missing_uploads' => :environment do
             end
 
             if upload_id.present?
-              PostUpload.create!(post_id: post.id, upload_id: upload_id)
+              attributes = { post_id: post.id, upload_id: upload_id }
+              PostUpload.create!(attributes) unless PostUpload.exists?(attributes)
             else
               missing_uploads << src
             end

GitHub sha: 8698a109