We (ftp.th.debian.org) have mirror backports for sometimes from
backports.org using normal ftpsync script, but pull request instead of
push one. The archive path we used was backports.org::backports.org.
But since 20th Sep, that path was not work anymore. The only archive
left as backports.org is backports.org::bpo-mirror. But that one need
password to access.
So, my question, if we would like to continue mirror backports,
which site we can use, or to whome we should contact to get rsync