Fix double feed stories in Phame

Summary:
Ref T9360. Fixes the double-rendering of post bodies in feed stories.

Downside is that 'publish' (on its own) no longer shows a body, but that seems fine.

Test Plan:

• Got some double bodies.
• Applied patch.
• No more double bodies.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9360

Differential Revision: https://secure.phabricator.com/D14748