Problem seems that from our CI systems this specific command does connect but does not download anything:
curl -o /dev/null --resolve ufpr.dl.sourceforge.net:80:184.108.40.206 -vvvv http:
The server seems to be located in Brazil sourceforge.c3sl.ufpr.br.
Seems like this sourceforge download is blocked by something.
I have the impression we do not need this download. Maybe we can work around this issue.