On a backport PR to 3.10 (e.g. #129440), and presumably to 3.9 too, Read the Docs will complain about a missing config key (before it gets to the `exit 183` telling it to not build anything for that branch). This shows up as a failed check in GHA. <!-- gh-linked-prs --> ### Linked PRs * gh-129510 * gh-130249 <!-- /gh-linked-prs -->