Not all package managers set DESTDIR
In the build-aux/meson/postinstall.py included with the Meson template, there's this check, which is used to disable some commands that are intended not to be run in package manager builds:
# Package managers set this so we don't need to run if not destdir:
But not all package managers set
DESTDIR (for example, Nix doesn't). Could there be another way (a Meson option?) to opt into this?