
Buildfarm members kittiwake, tadarida and snapper began to fail frequently when commits 3cd9c3b921977272e6650a5efbeade4203c4bca2 and f47ed79cc8a0cfa154dc7f01faaf59822552363f added tests of concurrency, but the problem was reachable before those commits. Back-patch to v10 (all supported versions). Discussion: https://postgr.es/m/20220116210241.GC756210@rfd.leadboat.com