Problem installing CSN 8 when Swarm 8 is the current version already

If you install Swarm 8 on a current CSN, and then try to install CSN 8 (which includes Swarm 8 already), you get this error:

# ./caringo-csn-bundle-install.sh

Error: Multilib version problems found.

This often means that multilib version-checking is indicating another problem, so the root cause is something else:

Missing Dependency — You have an upgrade for caringo-castor which is missing some dependency that another package requires. Yum is trying to solve this by installing an older version of caringo-castor of the different architecture. If you rerun the upgrade with a flag to exclude the bad architecture, yum will tell you what the root cause is (which package requires what): 
--exclude caringo-castor.otherarch

Duplicate Architectures — You have multiple architectures of caringo-castor installed, but yum can only see an upgrade for one of those architectures. If you don't need both architectures, remove the one with the missing update and everything will work.

Duplicate Versions — You have duplicate versions of caringo-castor installed already. Use "yum check" to see these errors. Do not use --setopt=protected_multilib=false to suppress checking: something else is likely to go wrong, causing more problems.

Protected multilib versions: caringo-castor-8.0-0.x86_64 != caringo-castor-8.0-1.x86_64
========================================================================
fatal: There were errors in the CSN installation. Please correct the errors and try again.

To fix this problem, remove the existing Swarm 8 version and re-run the installer.  

# yum remove caringo-castor-8.0-1.x86_64

After CSN installation, the CSN will reboot. Then, verify that the Swarm 8 version is selected: in the CSN UI, open the Netboot Management tab.