question about private repository image as FROM (slack invite in README is not valid anymore so can only ask here)

[freakhill]

I have an image with
FROM registry.abc.com/foo/bar

and a registry configuration {"registry.abc.com": {"foo/*": {"basic": {"username": "...", "password": "..." }}}}}}}

but the build fails with

{"level":"error","ts":1569407442.27974,"msg":"failed to execute build plan: execute stage: build stage 0: build node: do execute: execute step: get manifest: pull image registry.abc.com/foo/bar:latest: pull manifest: http send error: GET https://image registry.abc.com/v2/foo/bar/manifests/latest 401: {\"errors\":[{\"code\":\"UNAUTHORIZED\",\"message\":\"authentication required\",\"detail\":[{\"Type\":\"repository\",\"Class\":\"\",\"Name\":\"foo/bar\",\"Action\":\"pull\"}]}]}\n"}

The build is called via
docker run --rm --net host [...] gcr.io/makisu-project/makisu/$MAKISU_VERSION build --push="$TARGET_REGISTRY" [...] --docker-scheme="https" --registry-config="inline json from up there"

I know the config is ingested because a typo will result in an error...

Are private registries with basic auth supported as FROM images?