dot edge is not rendered correctly

[shiluotang]

digraph {
  rankdir=LR;
  node [ shape=record ];

  struct1 [
      label = "a|b|<port1>c";
  ];
  
  struct2 [
      label = "a|{<port2>b1|b2}|c";
  ];
  
  struct1:port1 -> struct2:port2 [ label="xyz" ];
}

is rendered as following, the edge does not comes from "c" part, but from the middle of struct1

According to https://sketchviz.com/graphviz-examples, it should be rendered as this (the right part, ignore the line style)