Problem
The setting max_oneboxes_per_post is not being honored in the composer preview.
Consequences
- the preview is not an accurate representation of what the post will look like
- disabling oneboxes for security reasons will not have any effect for post authors
Reproduction
Set max_oneboxes_per_post to zero, create a post with contents below and see what happens
https://www.youtube.com/watch?v=3BFTio5296w&list=RD3BFTio5296w&index=1