$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn1-10252-28827/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn1-10252-28827/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin c878e27d178fe1e9ca0f81336373476a901278a9:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         c878e27d178fe1e9ca0f81336373476a901278a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c878e27 bump release for test build