$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rouge.git /var/lib/mock/f45-build-35207-694/root/chroot_tmpdir/scmroot/rubygem-rouge
Cloning into '/var/lib/mock/f45-build-35207-694/root/chroot_tmpdir/scmroot/rubygem-rouge'...
$ git fetch origin f897fd8ef6a4f1864b9e22be39de7e27eb925d9c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rouge
 * [new ref]         f897fd8ef6a4f1864b9e22be39de7e27eb925d9c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f897fd8 5.1.0