Change 540749 had a related patch set uploaded (by DannyS712; owner: DannyS712):
[mediawiki/extensions/PageTriage@master] Enqueue: Don't allow enqueueing pages already in the queue

https://gerrit.wikimedia.org/r/540749

Change 540749 merged by jenkins-bot:
[mediawiki/extensions/PageTriage@master] Enqueue: Don't allow enqueueing pages already in the queue

https://gerrit.wikimedia.org/r/540749

Good stuff! Probably could use QA.

Using the API, I cannot requeue pages in the Article, User or Draft namespaces that are already in the queue.

I see the error: The page specified already exists in the pagetriage queue.

This change should not have a user-facing impact (unless the user also uses the API). It does not affect the UI.

I tested this on beta, but I believe it should be on production now.

{
    "error": {
        "code": "bad-pagetriage-enqueue-alreadyqueued",
        "info": "The page specified already exists in the pagetriage queue",
        "*": "See https://en.wikipedia.org/w/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce> for notice of API deprecations and breaking changes."
    },
    "servedby": "mw1343"
}

confirmed to be working