Redux: Posting sometimes doesn't clear the saved post

[cellio]

meta:293215

#538 seems to be happening again, non-deterministically. Sometimes a user posts an answer successfully, but the draft of that answer is still in the answer box on the page. The problem has been seen in multiple browsers by multiple people.

We don't want to discard drafts prematurely of course, but after the post is made it would be safe to discard the draft. Maybe we have an ND timing issue here?

Possibly related: https://meta.codidact.com/posts/293237