Ned: """In general, we don't test or claim to support building for a deployment target lower than the system being built on."""

This is not convincing, because the cpython builds are always
against <$ MACOSX_DEPLOYMENT_TARGET=10.6> .

Other builds use the current OS deployment. See for instance homebrew.
My script uses them all, from a 10.9 version.
This is because I never know what users use for building, and I don't care and build just everything.

By your default builds that are uploaded, you do claim that things build for 10.6 exactly, and nothing else.

I just think that all targets for all versions should build.

Am I mistaken here?