$ git clone -n https://src.fedoraproject.org/rpms/R-littler.git /var/lib/mock/f42-build-side-110318-58925371-6569303/root/chroot_tmpdir/scmroot/R-littler
Cloning into '/var/lib/mock/f42-build-side-110318-58925371-6569303/root/chroot_tmpdir/scmroot/R-littler'...
$ git fetch origin 38dacaf755fccf05f7c074bc04bd8c974ccdd485:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-littler
 * [new ref]         38dacaf755fccf05f7c074bc04bd8c974ccdd485 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 38dacaf R-maint-sig mass rebuild