the file "graph.dot" contains the graph which causes the bug. within the graph described by this file there is a node:
contained within the subgraph "main_layer".
"bomberman.server.ai" [ color = palegoldenrod, style = filled, width = "2.09" ];
after moving this node into the "unassigned_layer" subgraph, the bug doesn't appear anymore.
i reconstructed the bug with dotty.
Input file: b304.dot
[erg] Note that the crash occurs on irix as well.
[kowalski] A graph can't be laid out if there are two nodes in the same subgraph
which have directed edges from one node to the other and the constraint
is set to false. b304a.dot. is a smaller example.