$ git clone -n https://github.com/xcp-ng-rpms/kernel.git /var/lib/mock/v8.3-incoming-8921-27871/root/chroot_tmpdir/scmroot/kernel
Cloning into '/var/lib/mock/v8.3-incoming-8921-27871/root/chroot_tmpdir/scmroot/kernel'...
$ git fetch origin 2fc31b34c745a321bcc64ec41a20f9436d4d5199:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/kernel
 * [new ref]             2fc31b34c745a321bcc64ec41a20f9436d4d5199 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2fc31b34c Merge pull request #21 from xcp-ng-rpms/8.3-cve-2020-28374