$ git clone -n https://src.fedoraproject.org/rpms/rb_libtorrent.git /var/lib/mock/f41-build-832444-157403/root/chroot_tmpdir/scmroot/rb_libtorrent
Cloning into '/var/lib/mock/f41-build-832444-157403/root/chroot_tmpdir/scmroot/rb_libtorrent'...
$ git fetch origin c906353f8a6ada8799fd2bb301ae45f848c44c5c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rb_libtorrent
 * [new ref]         c906353f8a6ada8799fd2bb301ae45f848c44c5c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c906353 fix