Comment # 10 on bug 1153557 from Michael Andres

Then it's somehow ruby-specific. 
> $ ruby ./tt.rb 
> Downloaded: /var/adm/mount/AP_0xUIA8UK/repodata/repomd.xml
> Size: 9636
> Downloaded: /var/adm/mount/AP_0xUIA8UK/repodata> /3ee02eaafe1f5e9a2019aae3e60a8c54590009ab26af32c0786cdcaf805122b7-primary.xml.gz
> Size: 0

but 
> $ zypper ar http://download.opensuse.org/distribution/leap/15.2/repo/oss zzz
> $ zypper ref zzz
> $ ll /var/cache/zypp/raw/zzz/repodata/3ee*
> -rw-r--r-- 1 root root 11622518 Oct 14 12:18 
> 3ee02eaafe1f5e9a2019aae3e60a8c54590009ab26af32c0786cdcaf805122b7-primary.xml.gz