$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v8.2-u-tescande1-8893-27847/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v8.2-u-tescande1-8893-27847/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 4cc2d3430c7c569b0db81e030012435c1a8544a9:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         4cc2d3430c7c569b0db81e030012435c1a8544a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4cc2d34 bump release for test build