By the way, we have the same kind of "problem" with the meson build. As we are deliberately not want to install src/test/modules, after b6a0d469cae and 0d237aeebaee we must add step "meson compile install-test-files" in order to "meson test -q --setup running" to be successful.
To be honest, this step is not obvious. Especially than there was no such step before. But docs and https://wiki.postgresql.org/wiki/Meson are completely silenced about it. -- Best regards, Maxim Orlov.