A recent change for 3.0 introduced counter fields for attachments and

screenshots, aiming to reduce queries on review requests and to simplify

publishing changes. The publishing work introduced a bug where the

conditions required for turning draft captions into captions was not met

when adding attachments or screenshots to a review request that didn't

already have one.
This change fixes that bug and improves our unit tests, which weren't

catching this before partly due to not reloading the objects from the

database and partly due to not sanity-checking the resulting captions.

Created a review request and added some file attachments to it. Set the

captions and published the review request. Saw that the captions were

still present both for my user and an anonymous user (previously, they'd

show "No Caption").
Unit tests pass.