[Dot] Edge between clusters gets duplicated

[GadgetSteve]

Ported Issue from Mantis Original ID: 2455 Reported By: DelTree

SEVERITY: IMPORTANT Submitted: 2014-05-15 13:32:21

OS: DEBIAN GNU/LINUX

DESCRIPTION

An edge with [constraint=none] between two clusters gets duplicated.

STEPS TO REPRODUCE

The simplest file I found to exhibit the bug goes like this

digraph G
{
  subgraph cluster_G1
  {
    {
      rank=same;
      A -> B;
    }

    C -> A;
  }

  subgraph cluster_G2
  {
    {
      rank=same;
      D -> E;
    }

    F -> E;
  }

  B -> D [ constraint=none ];
}

then I build with

dot -Tpdf dupedge.gv -o dupedge.pdf

ADDITIONAL INFORMATION

I found the bug in debian version (2.26.3) and built version 2.38.0 to check. Same situation.