The packages in question that would need to be promoted appear to be cluster-glue and pacemaker. There's no problem with syncing or merging redhat-cluster first and letting it fail to build while the MIRs are processed; if nothing else, packages are not typically promoted to main until there is a reason to do so in the archive, so it's actually best to have the new redhat-cluster in place first so that it shows up on the archive administrators' report of packages that need to be promoted.
The packages in question that would need to be promoted appear to be cluster-glue and pacemaker. There's no problem with syncing or merging redhat-cluster first and letting it fail to build while the MIRs are processed; if nothing else, packages are not typically promoted to main until there is a reason to do so in the archive, so it's actually best to have the new redhat-cluster in place first so that it shows up on the archive administrators' report of packages that need to be promoted.