Graph with arrows doesn't render properly multiple branches from the same commit

[nicoespeon]

Arrow is expecting the branch dash to come vertically since commit is "pushed in Y".

Source code:

var gitgraph = new GitGraph({
  template: "blackarrow",
});

var master = gitgraph.branch("master")
master.commit();

var branch0 = master.branch("branch0")
branch0.commit();
master.commit();
branch0.commit();

var branch1 = branch0.branch("branch1")
master.merge(branch0)

var branch2 = branch1.branch("branch2")
var branch3 = branch1.branch("branch3")
branch3.commit().commit();
branch2.commit();
branch3.commit();
branch2.commit();