$ git clone -n https://github.com/xcp-ng-rpms/guest-templates-json.git /var/lib/mock/v8.3-incoming-9372-28125/root/chroot_tmpdir/scmroot/guest-templates-json
Cloning into '/var/lib/mock/v8.3-incoming-9372-28125/root/chroot_tmpdir/scmroot/guest-templates-json'...
$ git fetch origin 13873558e77f2162cc6be3985932545e41a00ed7:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/guest-templates-json
 * [new ref]         13873558e77f2162cc6be3985932545e41a00ed7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1387355 Merge pull request #15 from xcp-ng-rpms/gdy-XS-1541-XCPNG-1221