$ git clone -n https://github.com/xcp-ng-rpms/xcp-ng-release /var/lib/mock/v8.3-incoming-9683-28404/root/chroot_tmpdir/scmroot/xcp-ng-release
Cloning into '/var/lib/mock/v8.3-incoming-9683-28404/root/chroot_tmpdir/scmroot/xcp-ng-release'...
$ git fetch origin 38dc8fbe5bb624a728b06c17d66f6ae0fc3c90b5:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xcp-ng-release
 * [new ref]         38dc8fbe5bb624a728b06c17d66f6ae0fc3c90b5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 38dc8fb Remove noise from patches using git-format-patch options