While done some safety checks on the 1.36.0 release, I noticed the patch from 1.36.0-rc.0 was rather large:
-rw-rw-r-- 1 reedy reedy 1011137 May 27 20:53 mediawiki-1.36.0.patch.gz $ wc -l mediawiki-1.36.0.patch 131694 mediawiki-1.36.0.patch
Sure, Timeless had been rebranched, but everything else hadn't, but there were a load of commits being brought in to both Skins and Extensions on their first submodule bump
e.g.
https://github.com/wikimedia/mediawiki/commit/ace61df6c9c16d9f60c47ca738679d4445d508a9#diff-20ef7739e8423f114899b767909a220c5dc4169d73a38196d7a2dbfac5166c4e
https://github.com/wikimedia/mediawiki/commit/24ec2d544f5de0d0867df1b0ba12cf3490c0d159#diff-20ef7739e8423f114899b767909a220c5dc4169d73a38196d7a2dbfac5166c4e
https://github.com/wikimedia/mediawiki/commit/1fbfae290bd7c78ce171ed6bd52de83e663a8bbc#diff-20ef7739e8423f114899b767909a220c5dc4169d73a38196d7a2dbfac5166c4e
It would seem the commits are *right* now, but they weren't before... Why weren't they?
For example, MediaWiki-extensions-Interwiki was at rEIWA8121d9a4a784: Localisation updates from https://translatewiki.net. (May 2020) before, now it's at rEIWA38ddf24041d8: build: Updating browserslist to 4.16.6 (from yesterday).
May 2020 sounds MW-1.35-release terroritory...
rEIWA8121d9a4a784: Localisation updates from https://translatewiki.net. is in the REL1_35 branch.
Looking at the REL1_35 release branch in MW core... OATHAuth did something similarly "odd" in https://github.com/wikimedia/mediawiki/commit/37ef236f0c882426dd362e147779c992426d6b9d#diff-20ef7739e8423f114899b767909a220c5dc4169d73a38196d7a2dbfac5166c4e and ConfirmEdit in https://github.com/wikimedia/mediawiki/commit/8afdcfa3a341068b29f247246630f86acb60c8fc#diff-20ef7739e8423f114899b767909a220c5dc4169d73a38196d7a2dbfac5166c4e and LocalisationUpdate in https://github.com/wikimedia/mediawiki/commit/9da1df824eab900961c96fa331dbc8f5acf45578#diff-20ef7739e8423f114899b767909a220c5dc4169d73a38196d7a2dbfac5166c4e etc