$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo /var/lib/mock/v9.0-u-ydi1-11221-29597/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v9.0-u-ydi1-11221-29597/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin 3226de5609ad6de155475570b9f8b7885f2a58fe:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         3226de5609ad6de155475570b9f8b7885f2a58fe -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3226de5 bump release for test build