$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-incoming-11586-29880/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-incoming-11586-29880/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin b88bc883f18465a3f475ad42f430945ffc2895b8:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         b88bc883f18465a3f475ad42f430945ffc2895b8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b88bc88 Rebase patches on top of 26.1.4