As we announced/released 6.9 today (https://lists.centos.org/pipermail/centos-announce/2017-April/022351.html) , we reflected that in the internal mirror used by koji/cbs.centos.org so from now on, all built content will be built against 6.9.

We regenerated also all the metadata from within koji to reflect this.

Should you have issues, feel free to discuss those on this list, or #centos-devel on irc.freenode.net