[EPEL-devel] how to do epel8 fedpkg mockbuild?

[Dave Love]

What do you need to do these days to run an epel-8 mock build?
fedpkg mockbuild fails for me with

Error: Error downloading packages:
  Status code: 403 for https://infrastructure.fedoraproject.org/repo/rhel/rhel8/koji/latest/x86_64/... (IP: 38.145.60.16)

I configured a RHEL subscription key so that I can make a rhel-8 root
successfully.