crane: mutate and append adds layer with docker mediaType regardless of what base image uses #1427
Description
Describe the bug
mutate or append adds new layers as DockerLayer instead of OCILayer when the base image only has OCI mediaTypes.
This behavior leads to mixed mediaTypes.
To Reproduce
crane mutate thesayyn/debian:oci --append <some>.tar. <your-registry>:oci-mixed
Expected behavior
The newly added layer should have the mediaType application/vnd.oci.image.layer.v1.tar+gzip instead of application/vnd.docker.image.rootfs.diff.tar.gzip. Perhaps this could be controlled by a global flag? Maybe --preferred-media-types=oci|docker?
Additional context
Add any other context about the problem here.
- Output of
crane version: 0.11.0 - Registry used (e.g., GCR, ECR, Quay): Docker