Direct acyclic graph fails to render

[KommuSoft]

The following graph seems to break:

n1 = Node('N1')
n2 = Node('N2')
n3 = Node('N3')
n4 = Node('N4')
n5 = Node('N5')
n6 = Node('N6')
n7 = Node('N7')
n8 = Node('N8')
n9 = Node('N9')
n10 = Node('N10')
n11 = Node('N11')
n12 = Node('N12')
n13 = Node('N13')
n14 = Node('N14')
n15 = Node('N15')
n16 = Node('N16')
n17 = Node('N17')
n18 = Node('N18')
n19 = Node('N19')
n20 = Node('N20')
n21 = Node('N21')
n22 = Node('N22')
n23 = Node('N23')
n24 = Node('N24')
n25 = Node('N25')
n26 = Node('N26')
n27 = Node('N27', parents=[n1, n2, n3, n4, n5, n6, n7, n8, n9, n10, n11, n12, n13, n14, n15, n16, n17, n18, n19, n20, n21, n22, n23, n24, n25, n26])
n28 = Node('N28', parents=[n27])
n29 = Node('N29', parents=[n27])
n30 = Node('N30', parents=[n28, n29])
n31 = Node('N31', parents=[n30])
n32 = Node('N32', parents=[n31])
n33 = Node('N33', parents=[n32, n31])
n34 = Node('N34', parents=[n30])
n35 = Node('N35', parents=[n34])
n36 = Node('N36', parents=[n35, n34])
n37 = Node('N37', parents=[n30])
n38 = Node('N38', parents=[n37])
n39 = Node('N39', parents=[n38, n37])
n40 = Node('N40', parents=[n1, n2, n3, n4, n5, n6, n7, n8, n9, n10, n11, n12, n13, n14, n15, n16, n17, n18, n19, n20, n21, n22, n23, n24, n25, n26, n33, n36, n39])
n41 = Node('N41', parents=[n40, n27])
graph = Graph()
graph.show_nodes([n41])

whereas GrapViz suggests that this is still a DAG:

digraph {N1;N2;N3;N4;N5;N6;N7;N8;N9;N10;N11;N12;N13;N14;N15;N16;N17;N18;N19;N20;N21;N22;N23;N24;N25;N26;N27;N28;N29;N30;N31;N32;N33;N34;N35;N36;N37;N38;N39;N40;N41;N1 -> N27;N2 -> N27;N3 -> N27;N4 -> N27;N5 -> N27;N6 -> N27;N7 -> N27;N8 -> N27;N9 -> N27;N10 -> N27;N11 -> N27;N12 -> N27;N13 -> N27;N14 -> N27;N15 -> N27;N16 -> N27;N17 -> N27;N18 -> N27;N19 -> N27;N20 -> N27;N21 -> N27;N22 -> N27;N23 -> N27;N24 -> N27;N25 -> N27;N26 -> N27;N27 -> N28;N27 -> N29;N28 -> N30;N29 -> N30;N30 -> N31;N31 -> N32;N32 -> N33;N31 -> N33;N30 -> N34;N34 -> N35;N35 -> N36;N34 -> N36;N30 -> N37;N37 -> N38;N38 -> N39;N37 -> N39;N1 -> N40;N2 -> N40;N3 -> N40;N4 -> N40;N5 -> N40;N6 -> N40;N7 -> N40;N8 -> N40;N9 -> N40;N10 -> N40;N11 -> N40;N12 -> N40;N13 -> N40;N14 -> N40;N15 -> N40;N16 -> N40;N17 -> N40;N18 -> N40;N19 -> N40;N20 -> N40;N21 -> N40;N22 -> N40;N23 -> N40;N24 -> N40;N25 -> N40;N26 -> N40;N33 -> N40;N36 -> N40;N39 -> N40;N40 -> N41;N27 -> N41;}

(can be vizualized here: https://dreampuf.github.io/GraphvizOnline/#digraph%20%7BN1%3BN2%3BN3%3BN4%3BN5%3BN6%3BN7%3BN8%3BN9%3BN10%3BN11%3BN12%3BN13%3BN14%3BN15%3BN16%3BN17%3BN18%3BN19%3BN20%3BN21%3BN22%3BN23%3BN24%3BN25%3BN26%3BN27%3BN28%3BN29%3BN30%3BN31%3BN32%3BN33%3BN34%3BN35%3BN36%3BN37%3BN38%3BN39%3BN40%3BN41%3BN1%20-%3E%20N27%3BN2%20-%3E%20N27%3BN3%20-%3E%20N27%3BN4%20-%3E%20N27%3BN5%20-%3E%20N27%3BN6%20-%3E%20N27%3BN7%20-%3E%20N27%3BN8%20-%3E%20N27%3BN9%20-%3E%20N27%3BN10%20-%3E%20N27%3BN11%20-%3E%20N27%3BN12%20-%3E%20N27%3BN13%20-%3E%20N27%3BN14%20-%3E%20N27%3BN15%20-%3E%20N27%3BN16%20-%3E%20N27%3BN17%20-%3E%20N27%3BN18%20-%3E%20N27%3BN19%20-%3E%20N27%3BN20%20-%3E%20N27%3BN21%20-%3E%20N27%3BN22%20-%3E%20N27%3BN23%20-%3E%20N27%3BN24%20-%3E%20N27%3BN25%20-%3E%20N27%3BN26%20-%3E%20N27%3BN27%20-%3E%20N28%3BN27%20-%3E%20N29%3BN28%20-%3E%20N30%3BN29%20-%3E%20N30%3BN30%20-%3E%20N31%3BN31%20-%3E%20N32%3BN32%20-%3E%20N33%3BN31%20-%3E%20N33%3BN30%20-%3E%20N34%3BN34%20-%3E%20N35%3BN35%20-%3E%20N36%3BN34%20-%3E%20N36%3BN30%20-%3E%20N37%3BN37%20-%3E%20N38%3BN38%20-%3E%20N39%3BN37%20-%3E%20N39%3BN1%20-%3E%20N40%3BN2%20-%3E%20N40%3BN3%20-%3E%20N40%3BN4%20-%3E%20N40%3BN5%20-%3E%20N40%3BN6%20-%3E%20N40%3BN7%20-%3E%20N40%3BN8%20-%3E%20N40%3BN9%20-%3E%20N40%3BN10%20-%3E%20N40%3BN11%20-%3E%20N40%3BN12%20-%3E%20N40%3BN13%20-%3E%20N40%3BN14%20-%3E%20N40%3BN15%20-%3E%20N40%3BN16%20-%3E%20N40%3BN17%20-%3E%20N40%3BN18%20-%3E%20N40%3BN19%20-%3E%20N40%3BN20%20-%3E%20N40%3BN21%20-%3E%20N40%3BN22%20-%3E%20N40%3BN23%20-%3E%20N40%3BN24%20-%3E%20N40%3BN25%20-%3E%20N40%3BN26%20-%3E%20N40%3BN33%20-%3E%20N40%3BN36%20-%3E%20N40%3BN39%20-%3E%20N40%3BN40%20-%3E%20N41%3BN27%20-%3E%20N41%3B%7D )