$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10007-28659/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10007-28659/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 4602b8f2e002059809675f33ac28d38cb302a454:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         4602b8f2e002059809675f33ac28d38cb302a454 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4602b8f bump release for test build