Istio 1.13.4 build debug and distroless variants

We have a build pipeline which builds both distroless and non distroless version of istio images. Post Istio 1.13.4 upgrade we realized the same behavior does not work. At any point we are only able to get the default variant built either distroless or non distroless. Tried the build with various permutations of environment variables in istio-docker file like below. Can you point out what is missing here?

Note: Also FYI even to build distroless images as default we had to update PrimaryVariant in types.go to DistrolessVariant. Updating istio-docker does not seem to work for us