See review D39306 for patch and description. exp-run requested to check for build processes basing their default bytecode-writing decisions on this environment variable, causing plist mismatches.
This does not depend on bytecode existing or not, thus it does not depend on the trigger. All this does is ensure that the default bytecode-writing behaviour is disabled during a build to prevent (further) filesystem pollution, particularly when running as root.
To clarify: we pass explicit flags in build frontends during do-build/do-stage for packaged bytecode; this change does not affect that.
py-setuptools fails to package: https://pkg-status.freebsd.org/gohan05/data/131amd64-default-foo/2023-04-05_13h33m45s/logs/errors/py39-setuptools-63.1.0.log
this will probably never be committed so it blocks nothing.
(In reply to Antoine Brodin from comment #4) This will be committed when the proper time and resources to work on this become available again, which is around now. But this shouldn't block any individual ports.