$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v8.3-u-abourgeois1-8873-27830/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v8.3-u-abourgeois1-8873-27830/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 97a3e6f4aca280c69e70b8c1e9ce665979b49ce7:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         97a3e6f4aca280c69e70b8c1e9ce665979b49ce7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 97a3e6f bump release for test build