$ git clone -n https://github.com/xcp-ng-rpms/coreutils.git /var/lib/mock/v8.3-u-pcoval2-10388-28949/root/chroot_tmpdir/scmroot/coreutils
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10388-28949/root/chroot_tmpdir/scmroot/coreutils'...
$ git fetch origin f973b2266afa103d5216d4cc80c90835b4d521e9:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/coreutils
 * [new ref]         f973b2266afa103d5216d4cc80c90835b4d521e9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f973b22 bump release for test build