Gutenberg Branches are selectable but not Core ones

[SirLouen]

According to the PR #2868 the idea was that ?core-branch worked simialrly to ?gutenberg-branch but it seems that core-branch has not made it through

Now this PR has been deployed
https://make.wordpress.org/playground/2025/11/26/preview-gutenberg-development-branches-in-your-browser/

But Core trunk branch is not working
http://playground.wordpress.net/?core-branch=trunk

It seems that the proxy is handling correctly the trunk branch
https://playground.wordpress.net/plugin-proxy.php?org=WordPress&repo=wordpress-develop&workflow=Test%20Build%20Processes&artifact=wordpress-build-&branch=trunk

Apparently is working
https://playground.wordpress.net/?blueprint-url=https%3A%2F%2Fgist.githubusercontent.com%2FSirLouen%2Feeb880d82ac1e5b48b95934248bc39a6%2Fraw%2F5c8f722291fd66293fef511b81ca388c7b123195%2Fgistfile1.txt

PS: It seems that with ?wp=
It works the same as it was intended with ?core-branch
https://playground.wordpress.net/?wp=trunk

But I'm curious why core-branch is not working, apparently the code in packages/playground/website/src/lib/state/url/resolve-blueprint-from-url.ts looks right.