$ git clone -n https://github.com/xcp-ng-rpms/opam /var/lib/mock/v9.0-u-ydi1-11208-29593/root/chroot_tmpdir/scmroot/opam
Cloning into '/var/lib/mock/v9.0-u-ydi1-11208-29593/root/chroot_tmpdir/scmroot/opam'...
$ git fetch origin dcc10c7b0985626035df8239efe76c253f6da598:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/opam
 * [new ref]         dcc10c7b0985626035df8239efe76c253f6da598 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dcc10c7 bump release for test build