$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10109-28726/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10109-28726/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin cc3b396b6888503425ecd1ad748ee984a448d99c:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         cc3b396b6888503425ecd1ad748ee984a448d99c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cc3b396 bump release for test build