The trouble in init_rank bug has persisted for quite some time (see
https://gitlab.com/graphviz/graphviz/-/issues/1213).
Here is a set of input files that trigger that bug:
init_rank_1.gv
init_rank_2.gv
init_rank_3.gv
init_rank_4.gv
init_rank_5.gv
init_rank_6.gv
init_rank_7.gv
init_rank_8.gv
init_rank_9.gv
init_rank_10.gv
init_rank_11.gv
init_rank_12.gv
init_rank_13.gv
init_rank_14.gv
init_rank_15.gv
init_rank_16.gv
init_rank_17.gv
init_rank_18.gv
init_rank_19.gv
init_rank_20.gv
init_rank_21.gv