[opensuse-buildservice] build specific distros only on specific workers (workerhostcheck?)

Hi, our local OBS has quite different workers running on different Linux systems. RHEL6 seems to use something called xz-utils to compress rpm cpio archives. Unfortunately these are not available on some Linux distros. I noticed, that there's a #our workerhostcheck = 'my_check_script'; in BSConfig.pm How is that supposed to work? Or is there any other option to achieve that? -- With best regards, Carsten Hoeger