$ git clone -n https://github.com/xcp-ng-rpms/opam /var/lib/mock/v9.0-incoming-11330-29648/root/chroot_tmpdir/scmroot/opam
Cloning into '/var/lib/mock/v9.0-incoming-11330-29648/root/chroot_tmpdir/scmroot/opam'...
$ git fetch origin 685228182ee14c7365bdc6629ce875eb4fa2cb05:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/opam
 * [new ref]         685228182ee14c7365bdc6629ce875eb4fa2cb05 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6852281 Merge pull request #3 from xcp-ng-rpms/ydi/9