system upgrade failure: "Failed to synchronize cache for repo 'my', disabling."

[Sam Varshavchik]

An attempt to upgrade failed, logging the following entries:

dnf[910]: Failed to synchronize cache for repo 'my', disabling.

Followed by a bunch of:

"Unable to match package <name>"

and

"Error: Unable to match some of packages"

The "my" repo contains locally-built packages. The repo is on the server  
being upgraded here. Normally, apache starts and provides access to the repo  
over http. Nothing exotic.
 
system-upgrade downloaded all the packages from the "my" report without any  
problems, but "system-upgrade reboot" apparently rebooted the server, and  
the reboot apparently tried to sync again with the repo, but, of course,  
since the repo is down it failed.

So, how can I proceed with the upgrade, with this situation? Copy the "my"  
repo to another server, and point to it? That seems awkward. Why is "system  
upgrade" reboot trying to resync everything, that should've been  
"download"'s job, I would think.