By the way, I prepared but never uploaded 25.3.20-1 to Debian because of the armhf failure. Somehow my brain didn't connect this bug report Steve with the downstream Ubuntu packager Steve until now, but now as my brain seems to work again I tested this patch.
Here are two build where the only change is applying the patch and armhf started working with no visible regressions: https://launchpad.net/~mysql-ubuntu/+archive/ubuntu/mariadb-10.1/+builds?build_text=&build_state=all The same patch is in Ubuntu via https://launchpad.net/ubuntu/+source/galera-3/25.3.19-2ubuntu4 so it has recieved a fair amount of testing there too.
