You cannot build/re-build anything that has to be downloaded from dl1.centos-webpanel.com, it seems that the host has some network problems. Watching the logs, it can be seen that the server tries to download the packages, but the connection resets almost every time. After 5 failed requests, the log says: Cannot download, giving up, continue with the build.
The build fails because of this, but the return message is : Build complete.
I think this is not a dinamically message, because it will say that the build is complete even if there are a lot of errors.