$ git clone -n https://github.com/xcp-ng-rpms/xcp-emu-manager.git /var/lib/mock/v8.3-incoming-9939-28628/root/chroot_tmpdir/scmroot/xcp-emu-manager
Cloning into '/var/lib/mock/v8.3-incoming-9939-28628/root/chroot_tmpdir/scmroot/xcp-emu-manager'...
$ git fetch origin 82619e2950f2c3161cbbd4bd67f434609e379fb0:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xcp-emu-manager
 * [new ref]         82619e2950f2c3161cbbd4bd67f434609e379fb0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 82619e2 updated spec + new source