Adapt to Alpine's "dynamic downstream pipelines"
mrtest on Alpine is basically broken since Alpine switched to dynamic downstream pipelines in https://gitlab.alpinelinux.org/alpine/aports/-/commit/08d03b91a8680f30c23cff24f6f4be43d326636f
mrtest on Alpine is basically broken since Alpine switched to dynamic downstream pipelines in https://gitlab.alpinelinux.org/alpine/aports/-/commit/08d03b91a8680f30c23cff24f6f4be43d326636f