$ git clone -n https://github.com/xcp-ng-rpms/xcp-emu-manager.git /var/lib/mock/v8.3-incoming-9935-28628/root/chroot_tmpdir/scmroot/xcp-emu-manager
Cloning into '/var/lib/mock/v8.3-incoming-9935-28628/root/chroot_tmpdir/scmroot/xcp-emu-manager'...
$ git fetch origin f4af5bd9ac8257ab82eb0a2a6b091592dfc407e2:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xcp-emu-manager
 * [new ref]         f4af5bd9ac8257ab82eb0a2a6b091592dfc407e2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f4af5bd updated spec + new source