https://xpra.org/dists/CentOS/7/x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
Sorry about that and thanks for reporting it.
The repodata went missing as part of the re-signing of every package for #2445.
Try again and it should be OK now.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2446