Action does not push branches: Invalid branch name

Thanks for creating this action. For some of the repos I mirrored I get an error like this:

remote: GitLab: You cannot create a branch with an invalid name.
 ! [remote rejected] upstream/HEAD -> HEAD (pre-receive hook declined)

The error is quite inconsistent and it sometimes works on one of the consecutive runs of the pipeline. I looked into it and pushed refs individually. As far as I understand it, it sometimes has a symbolic ref upstream that it wants to push and this is the reason it fails.

I was able to fix the problem by recreating the functionality checking for non-symbolic refs:

 # Push only non-symbolic branches 
        - |
          if git for-each-ref refs/remotes/upstream| grep -q .; then
            branch_refs=$(git for-each-ref --format='%(refname) %(objecttype)' refs/remotes/upstream | grep ' commit$' | cut -d' ' -f1)
          else
            branch_refs=" "
          fi
        
        # Push only non-symbolic tags
        - |
          if git for-each-ref refs/tags | grep -q .; then
            tag_refs=$(git for-each-ref --format='%(refname) %(objecttype)' refs/tags | grep ' tag$' | cut -d' ' -f1)
          else
            tag_refs=""
            echo "No tags found"
          fi
        
        - |
          for ref in $branch_refs $tag_refs; do
            if [[ "$ref" == refs/remotes/upstream/* ]]; then
              shortname=${ref#refs/remotes/upstream/}
              target_ref="refs/heads/$shortname"
              echo "Pushing branch $ref -> $target_ref"
            elif [[ "$ref" == refs/tags/* ]]; then
              shortname=${ref#refs/tags/}
              target_ref="refs/tags/$shortname"
              echo "Pushing tag $ref -> $target_ref"
            else
              echo "Skipping unknown ref $ref"
              continue
            fi

            if git push origin "$ref:$target_ref" --force; then
              echo "✅ Success: $short name"
            else
              echo "❌ Failed: $shortname"
              failed=1
            fi
            echo "--------------------------"
          done

          if [ "$failed" -ne 0 ]; then
            echo "One or more pushes failed."
            exit 1
          fi

Has anyone else seen this error or has any other idea on how to fix this?