Post notices are not removed when ownership is changed

[Nacho_Caballero]

Steps to reproduce:

1. Create a new user and use it to create a new post (a .post-notice.new-user div will appear).

   

2. Change the ownership of the post to a frequent user

Expected behavior: the new user notice would disappear

Actual behavior: the new user notice remains (I believe the same would happen for the post-notice.returning-user div).