When the hub returns a fault, the xmlrpc decoder raises it and Koji catches this and converts the fault to one of its own exceptions if appropriate. If this ends in a traceback, python will show a complex chained traceback that includes the one raised by the decoder. This is never helpful.
This can show up in the ui like so https://koji.stg.fedoraproject.org/koji/taskinfo?taskID=110001220
Metadata Update from @tkopecek: - Custom field Size adjusted to None - Issue set to the milestone: 1.33
Metadata Update from @tkopecek: - Issue tagged with: testing-ready
Metadata Update from @mfilip: - Issue tagged with: testing-done
Commit 68f08612 fixes this issue
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/koji/koji/issues/3801
Please continue any further discussion there.