$ git clone -n https://src.fedoraproject.org/rpms/opam.git /var/lib/mock/f39-build-1863582-42526/root/chroot_tmpdir/scmroot/opam
Cloning into '/var/lib/mock/f39-build-1863582-42526/root/chroot_tmpdir/scmroot/opam'...
$ git fetch origin 4ec2a22db261de11b73f13153f1a56cff7d0224b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/opam
 * [new ref]         4ec2a22db261de11b73f13153f1a56cff7d0224b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4ec2a22 Rebuild for ocaml-ocamlgraph 2.1.0