Yeah, looks like mass rebuild just skips these packages:
https://pagure.io/releng/blob/master/f/scripts/mass-rebuild.py#_125
I am wondering if it wouldn't make sense to do a scratch build in that case
and proceed with normal FTBS policy [0] if it fails.
[0]
https://docs.fedoraproject.org/en-US/fesco/Fails_to_build_from_source_Fai...