Wallpost attachimage CSRF failure

Summary

Attaching an image to a wallpost fails.

Steps to reproduce

Try to attach an image to a new wallpost on the profile page.

What is the current bug behavior?

Server responds with HTTP 403, 'CSRF Failed: CSRF token missing or incorrect.'

The 'uploading...' spinner keeps spinning forever.

What is the expected correct behavior?

Image should be uploaded and attached.

Possible fixes

This probably broke in !3005 (merged)