Update to use the correct c/image/v4 import path, work originally from
https://github.com/containers/skopeo/pull/733 by Valentin Rothberg <rothberg@redhat.com>.
Signed-off-by: Miloslav Trmač <mitr@redhat.com>
Vendor the latest containers/image 50e5e55e46a391df8fce1291b2337f1af879b822
to enable parallel copying of layers.
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>
Temporarily vendor opencontainers/image-spec from a fork
to fix "id" value duplication, which is detected and
refused by gojsonschema now
( https://github.com/opencontainers/image-spec/pull/750 ).
Signed-off-by: Miloslav Trmač <mitr@redhat.com>
