oci: add workaround for containers/skopeo#2750

We're going to start referring to OCI images by their names starting
with `sha256:` (as podman names them in the `--iidfile`) soon.  Skopeo
doesn't like that, so add a workaround.

This will soon let us get rid of some of the hacking about we do in our
`examples/` build scripts.

Signed-off-by: Allison Karlitskaya <[email protected]>

Author: allisonkarlitskaya

crates/composefs-oci/src/skopeo.rs

@@ -48,6 +48,13 @@ impl<ObjectID: FsVerityHashValue> ImageOp<ObjectID> {
             None
         };
 
+        // See https://github.com/containers/skopeo/issues/2750
+        let imgref = if let Some(hash) = imgref.strip_prefix("containers-storage:sha256:") {
+            &format!("containers-storage:{hash}") // yay temporary lifetime extension!
+        } else {
+            imgref
+        };
+
         let config = match img_proxy_config {
             Some(mut conf) => {
                 if conf.skopeo_cmd.is_none() {