Copy federated graph to another variant?

I have a @current variant and I want to copy that in its entirety (including federation) to a new variant.

This is what I’m trying, but it’s copying over un-federated:

rover supergraph fetch "my-graph"@current \
| sed "s/.demo.svc.cluster.local/-$PR_NUMBER.svc.cluster.local/" \
| rover graph publish my-graph@"${VARIANT}" --schema -

The goal is to create a variant for feature-staging branches.