cmd-build: Conditionally change the packing structure of container-image

When the previous build exists, use its packing structure otherwise container-encapsulate
generates a new one

src/cmd-build

@@ -440,6 +440,12 @@ else
                  "--label=io.openshift.build.versions=machine-os=${buildid}"
                 )
     fi
+    previous_build=$(get_latest_build)
+    oci_tag=""
+    if [ -n "${previous_build}" ]; then
+      previous_builddir=$(get_build_dir "${previous_build}")
+      oci_tag+="--prior-build=oci-archive:${previous_builddir}/fedora-coreos-${previous_build}-ostree.${basearch}.ociarchive"
+    fi 
     runv rpm-ostree compose container-encapsulate --max-layers="$MAX_OSTREECONTAINER_LAYERS" --format-version=1 \
         --repo="${tmprepo}" \
         --label="coreos-assembler.image-config-checksum=${image_config_checksum}" \
@@ -448,6 +454,7 @@ else
         --label="org.opencontainers.image.revision=${config_gitrev}" \
         --copymeta-opt=fedora-coreos.stream \
         "${labels[@]}" \
+        "${oci_tag}" \
         "${buildid}" \
         oci-archive:"${ostree_tarfile_path}".tmp:latest
     /usr/lib/coreos-assembler/finalize-artifact "${ostree_tarfile_path}"{.tmp,}