oras doesn't push a file with 2 tags

[afdesk]

hi team! thanks for your really useful tool.

there is a problem with the latest version (0.13.0):
oras can't upload a file with 2 tags:

#!/bin/sh
tags=(latest 2)
for tag in ${tags[@]}; do
  oras push ghcr.io/afdesk/db-private:${tag} \
    --manifest-config /dev/null:application/vnd.afdesk.config.v1+json \
    db.tar.gz:application/vnd.afdesk.db.layer.v1.tar+gzip
done

the result:

$ ./up.sh 
Uploading cdbbe2e80b77 db.tar.gz
Exists    e3b0c44298fc 
Pushed ghcr.io/afdesk/db-private:latest
Digest: sha256:3d4023cb394a3d4dd5749be9b68af5a8e4869f4e9515cfc793e636616efc81f2
Exists    3d4023cb394a 
Pushed ghcr.io/afdesk/db-private:2
Digest: sha256:3d4023cb394a3d4dd5749be9b68af5a8e4869f4e9515cfc793e636616efc81f2

but it works correctly for version v0.12.0.

I hope it'll fix. thanks!

[qweeah]

Thanks @afdesk for reporting this issue, looking at this

[qweeah]

This should be a bug from oras-project/oras-go. @Wwwsylvia Can you take a look?

Reproduce Step

oras version: 0.13.0

1. Package an OCI artifact and push
   echo "test" > hi.txt && oras push $REG/$REPO hi.txt
2. Repush the artifact
   oras push $REG/$REPO:tag hi.txt
3. Push will be successful on client side but tag won't be created in the registry.

Root Cause

If a manifest blob is found existed (https://github.com/oras-project/oras-go/blob/main/copy.go#L154-L163), the copy process will be skipped as well as the retagging process.

[Wwwsylvia]

Thanks for reporting the issue! I will look into this next week.