oci: fix printing of "already" layer IDs

When we already have a layer, we print a message saying as much.  In
fb1de9f ("src/fsverity: up our FsVerityHashValue trait game") we
accidentally changed this to use the debug trait.  This would have been
correct if we were printing a layer ID, but this is an array, so we see
the bytes if we do that.  Revert to the previous behaviour.

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

Author: allisonkarlitskaya

src/oci/mod.rs

@@ -105,7 +105,7 @@ impl<'repo, ObjectID: FsVerityHashValue> ImageOp<'repo, ObjectID> {
 
         if let Some(layer_id) = self.repo.check_stream(layer_sha256)? {
             self.progress
-                .println(format!("Already have layer {layer_sha256:?}"))?;
+                .println(format!("Already have layer {}", hex::encode(layer_sha256)))?;
             Ok(layer_id)
         } else {
             // Otherwise, we need to fetch it...