$ git clone -n https://src.fedoraproject.org/rpms/caribou0.git /var/lib/mock/f39-build-2557548-62012/root/chroot_tmpdir/scmroot/caribou0
Cloning into '/var/lib/mock/f39-build-2557548-62012/root/chroot_tmpdir/scmroot/caribou0'...
$ git fetch origin b4b93e1ad3ed725a88f2a7e91c80522c1b375479:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/caribou0
 * [new ref]         b4b93e1ad3ed725a88f2a7e91c80522c1b375479 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b4b93e1 Added the README