$ git clone -n https://src.fedoraproject.org/rpms/cockpit-ostree.git /var/lib/mock/f42-build-3273925-41313/root/chroot_tmpdir/scmroot/cockpit-ostree
Cloning into '/var/lib/mock/f42-build-3273925-41313/root/chroot_tmpdir/scmroot/cockpit-ostree'...
$ git fetch origin 205d9fe09493a1945542088f54b93c34e8bd0fe9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cockpit-ostree
 * [new ref]         205d9fe09493a1945542088f54b93c34e8bd0fe9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 205d9fe Update to 207 upstream release