Make core wmf branches only use submodule branches that run with it in CI. E.g. if an extension with a branch named wmf/1.26wmf22 is run in CI it is only tested with other wmf22 branches, but if that branch is included as a submodule in core wmf24 then it was never tested against that branch. (Thank you @Krinkle for pointing out yesterday that we should improve that.)
From https://git.wikimedia.org/blob/mediawiki%2Ftools%2Frelease/269841a760da05bde32f782dcf7fe9fd28d56980/make-wmf-branch%2Fconfig.json
There is a list:
```
"special_extensions": {
"CentralNotice": "wmf_deploy",
"Wikidata": "wmf/1.26wmf22",
"SemanticMediaWiki": "1.8.x",
"SemanticResultFormats": "1.8.x",
"Validator": "0.5.x"
}
```
Semantic* are dealt with in T75940.
No idea about CentralNotice and Validator. Anyone?
Wikidata branches not every week, it might be fine to copy the old branch into the new one. Downside of that would be needing to sometimes backport to two branches which would double the work of a backport, but I'd prefer that over not properly testing with CI. mediawiki/tools/release seems to have an option for that (set the key from above to true instead of a string). I'd suggest to do that.