$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10312-28881/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10312-28881/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin c9bd0c18a247bc2b7469688df7461fa32364256e:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         c9bd0c18a247bc2b7469688df7461fa32364256e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c9bd0c1 bump release for test build