WP oEmbed: The embed-template 404 condition isn't getting triggered for 404'd embeds

[DrewAPicture]

When a post has been embedded and the permalinks have since been changed, an iframe with the 404 template for the embed site is displayed instead of triggering the 404 condition in embed-template.php.

Steps to reproduce:

1. Create a post.
2. Create a second post, embedding the first post.
3. Change the site's permastruct to something else
4. View the second post.

Expected: The 404 markup from embed-template.php
Actual: The general 404 markup for the the embed source site theme in an iframe.

Example post: ​http://wcpdx.trywpbeta.com/2015/10/testing-oembedding-of-posts/

[swissspidy]

It looks like this falls back to what #4328 describes: When the permalink structure changes, WordPress doesn't catch this and properly redirect to the new structure.

You have the same problem with any other rewrite endpoint, e.g. when accessing the post's comment feed under the old permalink structure.

Too late to fix that scenario in this cycle though. On the other hand, we could treat the embed endpoint as a special case, always setting is_embed to true when /embed/ is found in the request URL.

I'm not really familiar with the rewrite component, so if anyone wants to help out, let me know.

[DrewAPicture]

Punting pending further consideration of a good solution.

[swissspidy]

Suggesting close in favour of #34489

[swissspidy]

Of course I meant another ticket yesterday. Suggesting close in favour of #4328.

#9825 and #27019 are also very similar. This bug mentioned here is not specific to embeds after all.

[swissspidy]

Duplicate of #4328.