$ git clone -n https://src.fedoraproject.org/rpms/ocaml-gsl.git /var/lib/mock/f42-build-872272-177961/root/chroot_tmpdir/scmroot/ocaml-gsl
Cloning into '/var/lib/mock/f42-build-872272-177961/root/chroot_tmpdir/scmroot/ocaml-gsl'...
$ git fetch origin 5d2ea8e11bbee072fe972e8f6a7e1ee26586c38d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ocaml-gsl
 * [new ref]         5d2ea8e11bbee072fe972e8f6a7e1ee26586c38d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5d2ea8e Rebuild with gsl 2.8